Tesi: "ZnO/Ag" – Grafiati

1

Lucilha, Adriana Campano. "Nanocristais de ZnO e Ag-Ag2O-ZnO : síntese, caracterização heterogênea". Universidade Estadual de Londrina. Centro de Ciências Exatas. Programa de Pós-Graduação em Química, 2011. http://www.bibliotecadigital.uel.br/document/?code=vtls000184639.

Testo completo

Abstract (sommario):

Dentre os processos de oxidação avançados (POAs), a fotocatálise heterogênea mediada por óxidos semicondutores como ZnO e TiO2 tem sido muito efetiva na remoção de cor com baixo nível de contaminante. As caracterizações estruturais e morfológicas dos fotocatalisadores utilizados neste processo são importantes, pois o conhecimento da composição da camada superficial do sólido, viabiliza a compreensão da capacidade de adsorção e de fotocatálise. Este trabalho tem como objetivo sintetizar e caracterizar nanocristais de ZnO e Ag2O-ZnO obtidos em diferentes temperaturas e aplicar na fotocatálise do diazocorante direct red 23. A síntese de ZnO a partir de oxalato de zinco ocorre em temperatura de calcinação superior a 400ºC. Por outro lado, o oxalato misto de prata e zinco (Ag2C2O4 - ZnC2O4) calcinado a 400ºC produziu Ag, Ag2O e ZnO. A atividade fotocatalítica das amostras sintetizadas em diferentes temperaturas de calcinação foi investigada pela degradação do diazo corante direct red 23 (DR23), mantendo-se constante a concentração de corante 0,75x10-4 mol L-1 e utilizando-se 2,0 g L-1 do fotocatalisador a 30ºC. O ZnO calcinado a 600ºC apresentou o melhor kobs, sendo este, 3 vezes maior que ZnO calcinado a 800ºC. Com relação às amostras de ZnO sintetizadas na presença de Ag e Ag2O, o melhor valor de kobs foi observado para a amostra calcinada em 400ºC, sendo este 3,6 vezes maior que em 600ºC. A capacidade fotocatalítica dos materiais sintetizados foi prejudicada com a elevação da temperatura de calcinação, pois ocorre obstrução dos poros dos fotocatalisadores diminuindo, portanto, a área superficial específica. Assim, a mistura dos entre ZnO e Ag2O resulta em síntese viável para aplicação em fotocatálise heterogênea, pois a capacidade fotocatalítica de descoloração do diazocorante DR23 foi maior quando se utilizou este fotocatalisador quando comparado ao ZnO puro.
Among the advanced oxidation processes, AOPs, used for the color removal with low level of contaminant, the heterogeneous photocatalysis mediated by semiconductor oxides as ZnO and TiO2 have been very effective. The structural and morphological characterizations of the samples resulting of the syntheses are important, because the composition knowledge of the solid surface layer, it makes feasible the interaction comprehension with the substract and consequently of the adsorption and photocatalysis capacities. The characterizations were performed by X-ray diffraction, TGA/DTA thermal analysis, Raman scattering, X-ray dispersive energy spectrometry (EDX), scanning electronic microscopy (SEM), and textural analysis. This work has as the objective to synthesize and to characterize ZnO and Ag-Ag2O-ZnO nanocrystals, obtained in different temperatures and apply to the direct red 23 diazodye photocatalysis. The ZnO synthesis from the zinc oxalate occurs in calcinations temperature higher than 400ºC. On the other hand, the mixed oxalate of silver and zinc (Ag2C2O4 - ZnC2O4) calcinated at 400ºC produced Ag, Ag2O, and ZnO. The photocatalytic activity of the synthesized samples at different calcination temperatures was investigated by the direct red 23 diazodye (DR23), maintaining constant the azo dye concentration (0.75x10-4 mol L-1) and using photocatalyst (2.0 g L-1) at 30ºC.The calcinated ZnO at 600º C presented the best kobs, that is, three-fold larger than calcinated ZnO at 800ºC. With the respect to the ZnO samples synthesized in the presence of Ag and Ag2O, the best value of the rate constant was observed to the calcinated sample at 400ºC, being this 3.6 fold larger than at 600ºC. The photocatalytic capacity of the synthesized materials was prejudiced with the calcinations temperature elevation, because the obstruction occurs in the photocatalyst pores and decreasing, the specific surface area. So, the mixture between ZnO and Ag2O is a viable synthesis for application in heterogeneous photocatalysis, because DR23 azodye decolorization using this photocatalyst was higher when compared to pure ZnO.

Gli stili APA, Harvard, Vancouver, ISO e altri

2

Ibn, Mahrsi Mouna. "Nanohybrides ZnO/Ag ou ZnO/oxyde de cuivre pour applications photocatalytiques". Electronic Thesis or Diss., Université de Lorraine, 2024. http://www.theses.fr/2024LORR0044.

Testo completo

Abstract (sommario):

La croissance rapide de la population ainsi que l'industrialisation ont suscité des inquiétudes majeures quant à la disponibilité de l'énergie et à la pollution de l'environnement. La résolution de ces problèmes est au cœur de nombreuses recherches à l'échelle mondiale. L'énergie solaire, en tant que source d'énergie propre et pratiquement inépuisable, devrait être efficacement exploitée, notamment via des processus photocatalytiques, pour améliorer la dépollution environnementale. Les nanomatériaux hybrides, tels que ZnO/métal noble et ZnO/oxydes métalliques, se positionnent comme des candidats prometteurs pour atteindre ces objectifs car ils absorbent efficacement la lumière visible et permettent une séparation efficace des porteurs de charge. Ce mémoire est consacré au développement de nouveaux photocatalyseurs hétérostructurés pour la dégradation des polluants organiques. L'étude a exploré deux voies novatrices de synthèse de ZnO associé soit à des nanoparticules d'argent métallique soit à des oxydes de cuivre. Dans la première partie de cette mémoire, un procédé a été développé pour préparer des particules de ZnO d'environ 87 nm associées à des nanoparticules d'argent d'une taille moyenne de 2.7 nm. Cette stratégie met en œuvre la synthèse d'hydroxydes doubles lamellaires de zinc dopés à l'argent, suivie de la photodéposition des ions Ag+ en Ag(0), et enfin, la conversion par thermolyse de l'hydroxyde double lamellaire en oxyde de zinc. Dans la deuxième partie de la thèse, la photodéposition de nanoparticules de CuO-Cu₂O à la surface de ZnO a permis le développement d’hétérostructures avec une jonction p-n entre CuO-Cu₂O et ZnO. Les nouvelles méthodes de synthèse de catalyseurs hétérostructurés développées dans le cadre de cette thèse ont permis le développement de matériaux photocatalytiquement actifs pour la dégradation de polluants persistants en milieux aqueux. En termes de stabilité, ces catalyseurs peuvent être utilisés sur plusieurs cycles de dégradation sans perte notable d'efficacité. Le projet comporte également l'étude des différents paramètres expérimentaux afin d'optimiser les propriétés structurales, électroniques, optiques et photocatalytiques de ces matériaux
The fast growth of the population and industrialization have produced major concerns regarding energy availability and environmental pollution. Addressing these issues is at the forefront of global research. Solar energy, as a clean and almost infinite source, can be effectively harnessed through photocatalytic processes to contribute to environmental remediation. Hybrid nanomaterials, such as ZnO/noble metal and ZnO/metal oxides, emerge as promising candidates to achieve these goals due to their enhanced light absorption capability and excellent charge carrier separation. This thesis is dedicated to the development of new hybrid photocatalysts designed for the degradation of organic pollutants. The study explores two innovative synthesis pathways of ZnO, combined with photodeposited nanoparticles of metallic silver or copper oxide, onto ZnO. In the first part of the study, a solvothermal method was developed to prepare ZnO particles of approximately 87 nm associated with silver nanoparticles with an average size of 2.7 nm. This strategy involves the synthesis of silver-doped zinc double-layered hydroxides, followed by the photodeposition of Ag+ ions into Ag(0), and ultimately, the conversion through thermolysis of the double-layered hydroxide into ZnO. In the second part, the preparation via an environmentally friendly and easy photodeposition method was used to create heterostructured photocatalysts featuring a p-n junction between CuO-Cu₂O and ZnO. The novel synthesis methods for ZnO-based heterostructured catalysts developed in the framework of this thesis have led to the creation of nanohybrid materials exhibiting high efficiency in degrading persistent pollutants in aqueous environments. In terms of stability, these hybrid photocatalysts can be used over multiple degradation cycles without a significant loss of effectiveness. The project also involves the study of various experimental parameters to optimize the structural, electronic, and optical properties of the photocatalysts

Gli stili APA, Harvard, Vancouver, ISO e altri

3

Phillips, Charlotte Louise. "First principles modelling of the ZnO/Ag interfacial system". Thesis, University of Cambridge, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.611694.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

4

Theodorou, Ioannis. "Bioreactivity of ZnO and Ag nanostructures in the lung". Thesis, Imperial College London, 2015. http://hdl.handle.net/10044/1/43959.

Testo completo

Abstract (sommario):

One-dimensional nanomaterials (NMs) have become the focus of intensive research due to their unique physicochemical properties and their application in the fabrication of nanoscale devices. Silver (Ag) and zinc oxide (ZnO) nanowires (NWs) are considered as potential building blocks for the next generation of optical, electronic and sensing devices. However, there is currently limited information on human health effects from Ag and ZnO NW exposures, but concerns have been raised about a potentially greater toxicity compared to their non-fibrous counterparts. Inhalation of Ag and ZnO NWs represents one of the primary routes for human exposure. Due to their size, these NMs are expected to preferentially deposit in the alveolar region of the lungs, where any damage would not only impact pulmonary homeostasis but would also determine possible translocations to other organs. Therefore, the interactions of Ag and ZnO NWs with the pulmonary epithelium urgently need to be addressed, in order to predict their adverse effects and provide guidelines for their safe use. Along with concerns about the toxic effects of Ag NMs, there is also potential for enormous benefit via highly efficacious antibacterial modality. Bacterial infections of the pulmonary system, such as tuberculosis, are increasing; especially infections caused by bacterial strains resistant to existing conventional antibiotics. AgNPs represent exciting candidates for the development of novel platforms for the treatment of pulmonary bacterial infections. Whilst the biological activity of silver has been well demonstrated, the mechanisms by which AgNPs degrade at the bio-nano interface and how these processes correlate to their bioreactivity are poorly understood. The motivation of this thesis is to investigate the bioreactivity of Ag and ZnO nanostructures in the lungs. The main objective of the work presented here is to examine the bioreactivity of Ag and ZnO NWs with human lung epithelial cells from the perspective of their putative toxicity. For inhaled NMs that reach the alveoli, the lung lining fluid (LLF) that covers their surface represents a first line of defence of the lungs. Therefore, the emphasis of this work is placed on characterizing the impact of the LLF on the physicochemical properties of Ag and ZnO NWs. The formation of a phospholipid/protein corona is shown to modify the ion release kinetics and aggregation states of the NWs. These effects are correlated with the cellular uptake and toxicity of the NWs to human lung epithelial cells. Furthermore, the mechanisms by which Ag and ZnO NWs degrade within epithelial cells are investigated. In the case of AgNWs, intracellular dissolution precedes the precipitation of highly insoluble silver sulfide, which could significantly limit their short-term toxicological effects. ZnO NWs, on the other hand, rapidly dissolve intracellularly and cell death correlates with the amount of free Zn2+ ions released. Furthermore, the antibacterial effects of AgNPs against Mycobacterium tuberculosis (M.tb) are examined. A set of analytical transmission electron microscopy techniques are employed to investigate the ultrastructural damage in bacterial cells and the mechanisms by which AgNPs induce cell damage. The antimicrobial effects of AgNPs are also examined in M.tb-infected macrophages, to explore the potential use of AgNPs as therapeutic agents for pulmonary bacterial infections.

Gli stili APA, Harvard, Vancouver, ISO e altri

5

Azevedo, Carla Sofia Leite. "Toxicity of Ag decorated ZnO nanomaterials to Daphnia magna". Master's thesis, Universidade de Aveiro, 2015. http://hdl.handle.net/10773/15411.

Testo completo

Abstract (sommario):

Mestrado em Toxicologia e Ecotoxicologia
A nanotecnologia é uma área em crescimento e os nanomateriais (NMs) podem ser encontrados numa vasta variedade de produtos como equipamentos ou dispositivos médicos e cosméticos. Os NMs atraem muita atenção devido à sua grande reatividade, resultado da sua elevada área de superfície em relação ao seu volume. Eles podem apresentar diferentes composições químicas, tamanhos e formas, o que pode influenciar o seu comportamento. Devido ao aumento de produção e presença em bens de consumo, os NMs podem chegar ao ambiente devido a introdução direta ou indireta. Apesar de muitos estudos se focarem na toxicidade dos NMs, diferentes resultados podem ser encontrados para NMs com a mesma composição química. Isto deve-se principalmente à influência de fatores abióticos e bióticos que podem alterar a biodisponibilidade dos NMs e por conseguinte a sua toxicidade, assim como à diversidade de características que estes materiais podem apresentar. A presença de outros NMs ou químicos no ambiente pode influenciar a sua toxicidade, aumentando-a ou diminuindo-a. Para além disto, têm sido desenvolvidos novos NMs formados por vários nanomateriais, aumentando as suas funcionalidades em comparação com o(a)s NMs/NPs isolado(a)s. Por estas razões é importante perceber como se irão comportar no ambiente. Tendo isto em consideração, o principal objetivo deste trabalho foi avaliar a toxicidade de NMs compostos por ZnO-NM com Ag-NP na superfície (ZnO/Ag-NM) e tentar perceber se a toxicidade destes NMs pode ser prevista através da toxicidade individual dos seus componentes. Com este objetivo a toxicidade individual e em mistura de ZnO-NM e de Ag-NP foi avaliada no organismo Daphnia magna e posteriormente comparada com a toxicidade de ZnO/Ag-NM. Para isso, foram realizados testes de imobilização e reprodução. Para avaliar a toxicidade da mistura e dos ZnO/Ag-NM também foi utilizada a ferramenta informática MixTox, baseada no modelo de adição de concentração e foram explorados possíveis desvios como sinergismo/antagonismo (S/A), desvio dependente da dose (DL) e desvio dependente do ratio químico (DR). Os ZnO-NM e as Ag-NPs demonstraram um esperado aumento dose-resposta para Daphnia magna. Foi verificada, para ambos os NMs, uma diminuição da sobrevivência ao fim de 48h e uma diminuição do número de neonatos produzido durante 21 dias. As Ag-NPs foram as que demonstraram maior toxicidade. A mistura apresentou um desvio dependente da dose (DL) para a imobilização e para a reprodução foi observado sinergismo. Os ZnO/Ag-NMs apresentaram maior toxicidade do que os ZnO-NM individualmente. Quando os resultados foram analisados com o MixTox foi observado um desvio dependente do químico (DR) para a imobilização e um desvio dependente das doses usadas (DL) para a reprodução. Este estudo demonstra que tanto a mistura efetuada em laboratório como a previsão baseada nos resultados de toxicidade dos ZnO/Ag-NM não serão baseados no mesmo comportamento dos seus componentes e demonstra também a importância de ter em consideração a interação NM-NM aquando da avaliação da toxicidade dos NMs.
Nanotechnology is a rising field and nanomaterials (NMs) can now be found in a vast variety of products that can go from medical equipment to cosmetics. NMs attract much attention due to their high reactivity, a result of high surface area to volume ratio. They can present different chemical compositions, sizes and shapes which can alter their behaviour. Due to their increase of production and presence in consumer products, NMs can end up in the environment due to unintentional or intentional release. Although many studies have focused on the toxicity of NMs, different results can be found for NMs with the same chemical composition. This is due to the fact that abiotic and biotic factors can alter the NMs bioavailability and therefore their toxicity, along with the diversity of their inherent characteristics. The presence of other NMs or chemicals in the environment can also affect NMs toxicity, increasing or decreasing their toxicity. Also, new nanomaterials combining NM-NM are being development due to their enhancing characteristics when compared to NMs or nanoparticles (NPs) alone. Therefore, it is important to understand how they will behave in the environment. Taking this into account, the main objective of this work was to evaluate the toxicity of a NM composed by ZnO-NM with Ag-NP on its surface (ZnO/Ag-NM) and try to understand if its toxicity can be predicted by the toxicity of the single components. With this purpose, the toxicity in Daphnia magna was evaluated to ZnO-NM and Ag-NP as single components, as a laboratory mixture and then compared to the toxicity of the ZnO/Ag-NM. To assess toxicity, immobilization and reproduction tests were performed. Also, the mixture toxicity and the toxicity of the ZnO/Ag-NM were analysed using the MixTox tool, based on the concentration addition model and possible deviations for synergism/antagonism (S/A), dose-level (DL) and dose-ratio (DR) were explored. ZnO-NM and Ag-NPs showed an increase toxicity to Daphnia magna with increasing concentrations. Decrease of survival after 48h and decrease in the number of neonates produce during 21 days were observed for both NMs with Ag-NPs demonstrating the highest toxicity. The mixture exposures showed a deviation dependency on the doses used (DL) for immobilisation and for reproduction a synergism deviation was observed. ZnO/Ag-NM showed higher toxicity when comparing to the ZnO-NM alone. When analysing the results with the MixTox tool a deviation dependent on the chemical present (DR) was observed for immobilization and a dose level deviation (DL) for reproduction. This study demonstrates that both, the mixture and the ZnO/Ag-NM, will not behave as their components and the toxicity cannot be predicted by them, highlighting the importance of taking into account the interaction NM-NM when assessing NMs toxicity.

Gli stili APA, Harvard, Vancouver, ISO e altri

6

Singh, Jai, O. N. Srivastava, R. S. Tiwari e P. Kumar. "Structural and optical investigations of low temperature solution based synthesized ZnO and Ag admix ZnO nanoparticles (NPs)". Thesis, Видавництво СумДУ, 2011. http://essuir.sumdu.edu.ua/handle/123456789/20574.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

7

Опанасюк, Анатолій Сергійович, Анатолий Сергеевич Опанасюк, Anatolii Serhiiovych Opanasiuk, Олександр Ігорович Гузенко, Александр Игоревич Гузенко, Oleksandr Ihorovych Huzenko, Олександр Анатолійович Доброжан et al. "Чорнила на основі наночасток Ag, ZnO, Cu2ZnSnS4 для друку електронних схем". Thesis, Сумський державний університет, 2018. http://essuir.sumdu.edu.ua/handle/123456789/67837.

Testo completo

Abstract (sommario):

Останнім часом виготовлення елементів побуту переходить від адитивного методу виробництва до формування цілісного об’єкта методом 3D друку. Це пов’язано з тим, що цей метод дає змогу здешевити і пришвидшити виробництво, а в подальшому перенести виготовлення нескладних предметів побуту безпосередньо в людські домівки. Технологія друку чорнилами на основі наночастинок металів та напівпровідників дає змогу швидко та дешево створювати електричну розводку і напівпровідникові елементи приладів сенсорики, прозорої електроніки та геліоенергетики.

Gli stili APA, Harvard, Vancouver, ISO e altri

8

Londono, Zuluaga Nathalia. "Impacts of engineered nanoparticles (TiO2, ZnO, Ag) on aquatic microbial communities". OpenSIUC, 2016. https://opensiuc.lib.siu.edu/theses/1858.

Testo completo

Abstract (sommario):

The production and uses of engineered nanoparticles (ENPs) have been increasing with the expansion of science and technology, and their unavoidable disposal into the soil and waterways, eventually ended up in the ocean causes serious concerns about their potential hazards to the environment and human health. The need to comprehend the impacts of ENPs in our aquatic ecosystem has motivated this research to study: 1) effect of TiO2 on Crypthecodinium cohnii; 2) effects of TiO2 and ZnO on an aquatic microbial community simulating a static lake environment; and 3) effects of TiO2, ZnO and Ag on a microbial community simulating those in a river after receiving treated wastewater. The results showed for the first study that TiO2 at different concentrations (50 mg/L, 30 mg/L, 10 mg/L, 2 mg/L, 0.5 mg/L, and 0 mg/L) in a 10-day period of observation did not negatively affect either cell growth, substrate (glucose) utilization, cellular composition or lipid profile of C. cohnii. On the contrary, the size distribution and zeta potential of TiO2 demonstrated that at its highest concentration (50 mg/L), it might present an effect on the microalgae. However, there was not enough evidence to prove toxicity, since all of the other analysis performed confirmed no impact. The second experiment proved that TiO2 and ZnO had different effects on an aquatic microbial community at experimental dosages including river water without ENP addition, TiO2 at a final concentration of 700 µg/L, ZnO at 70 µg/L, and both TiO2 and ZnO at 700 µg/L and 70 µg/L, respectively. TiO2 alone had no effect on the relative abundance of bacterial species, but caused significant decrease and increase of the relative abundances of the Chlorophyte and Streptophyta phyla, respectively, compared with other treatments and controls. ZnO, both alone or together with TiO2, brought increased population within the phylum of Bacteroidetes and decreased population of three species: Mycobacterium riyadhense, Hyphomicrobium spp., and Verrucomicrobium spp. Taken as a whole, the interaction between TiO2 and ZnO was not significant in terms of each ENP’s physicochemical properties and toxicity toward the target microbial community. The third and last study investigated individual and combined effects from three ENPs: TiO2 (700 µg/L – 7,000 µg/L), ZnO (70 µg/L - 700 µg/L) and Ag (200 µg/L – 2,000 µg/L). ENPs at these doses were found to be impactful to the target bacterial community. Similarly, the Eukaryota kingdom was affected by the ENPs at all tested concentrations. Overall, this thesis established that parameters for studying ENPs such as dosage, primary particle size, light effect, exposure time, and species should be taken into considerations to assess their impacts due to their unique physical and chemical properties.

Gli stili APA, Harvard, Vancouver, ISO e altri

9

Rojas, Michea Carolina Valeria. "Actividad fotocatalítica de nanoestructuras ZnO y ZnO:M (M: Fe, Cu, Ag)". Tesis, Universidad de Chile, 2016. http://repositorio.uchile.cl/handle/2250/144084.

Testo completo

Abstract (sommario):

Magíster en Ciencias de la Ingeniería, Mención Ingeniería Química
En el presente trabajo de investigación se sintetizó materiales nanoestructurados de óxido de cinc mediante la técnica de sol gel. Con el objetivo de mejorar sus capacidades fotocatalíticas en la síntesis se incorporó cantidades conocidas de metales (dopaje), a saber, Cu, Fe y Ag, esto para producir cambios en su morfología y estructura cristalina. Se incorporó cobre en un 0.5, 1, 1.5 y 2% en fracción molar, hierro en un 0.25, 0.5, 0.75 y 2% en fracción molar y plata en un 0.5, 2, 3, 6 y 9% en fracción molar. Para caracterizar los materiales se realizó medidas de área superficial BET, microscopía electrónica de barrido, microscopía de transmisión electrónica, microscopía de transmisión electrónica de alta resolución, difracción de rayos X (DRX), fluorescencia de rayos X (FRX), espectroscopía infrarroja con transformada de Fourier (FTIR), espectroscopía micro-Raman, fotoluminiscencia (FL), y espectroscopía UV visible. Finalmente se llevaron a cabo pruebas de fotocatálisis con luz visible para evaluar las potenciales mejoras en el rendimiento de los materiales, y se determinaron las constantes cinéticas de aquellos que evidenciaron el mayor rendimiento en descontaminación de agua. Se obtuvo muestras de tamaño nanométrico con una morfología de partícula en el caso de hierro y plata. En el caso de cobre la morfología fue varillas. S observó que la incorporación de hierro y plata en el óxido de cinc favorecen la fotocatálisis, no así el cobre.

Gli stili APA, Harvard, Vancouver, ISO e altri

10

Гузенко, Олександр Ігорович, Александр Игоревич Гузенко, Oleksandr Ihorovych Huzenko, Станіслав Ігорович Кахерський, Станислав Игоревич Кахерский, Stanislav Igorevich Kakherskyi, Олександр Анатолійович Доброжан et al. "Газочутливий елемент детектора, створений методом друку з використанням наночорнил Ag та ZnO". Thesis, Сумський державний університет, 2020. https://essuir.sumdu.edu.ua/handle/123456789/80968.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

11

Gunputh, Urvashi Fowdar. "Antibacterial properties of TiO2 nanotubes coated with nano-ZnO and nano-Ag". Thesis, University of Plymouth, 2018. http://hdl.handle.net/10026.1/11155.

Testo completo

Abstract (sommario):

TiO2 nanotubes grown on titanium alloy are known to increase the biocompatibility of the alloy when used in dental/orthopaedic implants. Furthermore, their nanotubular structures can act as antibacterial agent carrier and as a scaffold for tissue engineering with the aim of adding antibacterial properties to the implant. This study aims at fabricating an antibacterial and biocompatible nanocomposite coating on Ti-6Al-4V involving nano-ZnO and nano-Ag. Initially, TiO2 nanotubes were self-assembled on the polished surface of medical grade Ti-6Al-4V alloy discs using anodisation. First silver nanoparticles were chemically reduced from silver ammonia using delta-δ-gluconolactone for different duration on the nanotubes to form TiO2-Ag composite coating. Nano HA was added to the latter coating with the aim of reducing toxicity from silver, hence forming TiO2-Ag-HA coating. Secondly, nano-ZnO was thermo-chemically grown on the TiO2 nanotubes using zinc nitrate and hexamethylenetetramine. They were then annealed at 350-550 oC hence forming TiO2-ZnO. HA was grown on the latter coating by a biomimetic method whereby the coated discs were placed in a concentrated simulated body fluid at 37 oC forming TiO2-ZnO-HA. The stability of the 4 coatings, TiO2-Ag, TiO2-Ag-HA, TiO2-ZnO and TiO2-ZnO-HA were assessed using the dialysis method (n=3 each) and then exposed to S.aureus for 24 hours in BHI broth. Their antibacterial properties were assessed using different assays and microscopic imaging with respect to different controls (n=6 each for assays and n=3 for imaging). Their biocompatibility properties were assessed in the presence of primary human osteoblast cells in DMEM media with the help of biochemical assays, molecular gene expression and microscopic imaging (n=3). Both silver and zinc coated nanotubes showed significant level of antibacterial properties with silver coating being more bactericidal than the coating containing zinc. Nonetheless, the zinc oxide coatings were more biocompatible than the silver coating. Nano silver and zinc oxide containing composite coatings were successfully synthesised and tested in the presence of bacteria and human cells. The final conclusion was that nano-silver was still toxic and nano-ZnO coatings were more biocompatible.

Gli stili APA, Harvard, Vancouver, ISO e altri

12

Santos, Patrícia Barros. "Estudo da fotodegradação no visível do corante Reactive Black 5 por catalisadores plasmônicos híbridos Ag∕ZnO e Cu∕ZnO". Universidade Federal de Juiz de Fora (UFJF), 2016. https://repositorio.ufjf.br/jspui/handle/ufjf/4408.

Testo completo

Abstract (sommario):

Submitted by Renata Lopes (renatasil82@gmail.com) on 2017-05-04T15:25:57Z No. of bitstreams: 1 patriciabarrossantos.pdf: 5111164 bytes, checksum: a7268529a7643972391f0dd226a987a3 (MD5)
Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2017-05-17T13:32:29Z (GMT) No. of bitstreams: 1 patriciabarrossantos.pdf: 5111164 bytes, checksum: a7268529a7643972391f0dd226a987a3 (MD5)
Made available in DSpace on 2017-05-17T13:32:29Z (GMT). No. of bitstreams: 1 patriciabarrossantos.pdf: 5111164 bytes, checksum: a7268529a7643972391f0dd226a987a3 (MD5) Previous issue date: 2016-07-28
CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
O presente trabalho consistiu na síntese e caracterização de catalisadores plasmônicos nanoestruturados híbridos metal∕semicondutor, para aplicação na fotodegradação do corante têxtil Reactive Black 5 (RB5), utilizando irradiação no visível. Foram sintetizadas nanopartículas de óxido de zinco, cobre (CuNPs) e prata (AgNPs), bem como catalisadores plasmônicos híbridos do tipo Cu∕ZnO e Ag∕ZnO que foram submetidos a diversas técnicas de caracterização como, espectroscopia Raman, UV-VIS, DRX de policristais, MEV e MET. Os processos de fotodegradação foram realizados em um reator labmade, no qual a solução de corante (1×10-5mol L-1) foi irradiada utilizando lâmpada fluorescente (11W) e∕ou incandescente (100W) como fontes de irradiação no visível. A fotodegradação do corante RB5 foi monitorada através de espectroscopia eletrônica no UV-VIS, espectroscopia vibracional Raman ressonante (RR) e intensificada por superfície (SERS), sendo possível observar mudanças relacionadas ao processo de fotodegradação. A espectroscopia no UV-VIS mostrou a queda na intensidade da banda de absorção do grupo cromóforo com o tempo de irradiação; por outro lado, RR e SERS permitiram observar a formação de espécies fluorescentes e mudanças no perfil espectral vibracional. Não ocorreu a fotólise do corante por nenhuma das duas fontes de irradiação utilizadas. AgNPs não promoveram a fotodegradação do RB5, porém nanopartículas de ZnO degradaram cerca de 66% das moléculas de corante, sob irradiação no visível (lâmpada incandescente). Fotocatalisadores plasmônicos do tipo Ag∕ZnO foram utilizados nos processos de degradação do RB5 utilizando ambas as fontes de irradiação no visível, sendo adicionados ao meio do corante de formas diferentes. Quando utilizado diretamente em suspensão e sob irradiação da lâmpada fluorescente o percentual de fotodegradação foi de 97%. Já com a adição do catalisador no estado sólido à solução de corante e sob irradiação da lâmpada fluorescente 72% das moléculas de RB5 foram degradadas. Esse último resultado pode ser comparado ao obtido utilizando ZnO como catalisador, e mostra um ganho de 22% na eficiência catalítica no visível na presença do material plasmônico AgNP/ZnO.
The present work consisted in the synthesis and characterization of plasmonic nanostructured hybrids metal∕semiconductor catalysts, for application on photodegradation of the Reactive Black 5 (RB5) textile dye using visible irradiation. Nanoparticles consisting of zinc oxide, copper (CuNPs) and silver (AgNPs) were synthesized, as well as plasmonics catalysts of Cu∕ZnO and Ag∕ZnO types. The materials underwent several characterizations using techniques such as Raman Spectroscopy, UV-VIS, polycrystal DRX, SEM and TEM. Photodegradation processes were carried out in a labmade reactor, in which a dye solution (1×10-5mol L-1) was irradiated using fluorescent (11W) and∕or glowing (100W) lamp bulb as sources of radiation in the visible range. The photodegradation of the RB5 dye was monitored through electronic spectroscopy UV-VIS, and vibrational spectroscopies resonant Raman (RR) and surface enhanced Raman spectroscopy (SERS). UV-VIS allowed observing changes related to the photodegradation process, as a drop in intensity of the absorption band of the chromophoric group. RR and SERS techniques results presented the formation of fluorescent species and changes in the vibrational spectral profile. The photolysis of the dye didn’t occur under any of the sources of irradiation used. AgNPs didn’t promote the photodegradation of the RB5, but nanoparticles of ZnO degraded about 66% of the dye molecules, under the visible radiation (incandescent lamp). Plasmonics photocatalysts Ag∕ZnO were used in the processes of degradation of the RB5 using both sources of irradiation in the visible range, but it was added to the dye solution in different ways. When used directly in suspension and under fluorescent lamp irradiation the photodegradation percentage was 97%. With the addition of the catalyst in the solid state to the dye solution and under fluorescent lamp irradiation 72% of the RB5 molecules were degraded. This last result can be compared to that achieved using ZnO as catalyst and shows a 22% gain in catalytic efficiency under visible light in the presence of the plasmonic material AgNP/ZnO.

Gli stili APA, Harvard, Vancouver, ISO e altri

13

Moreira, Micheline Dami?o Dias. "Rotas de s?nteses qu?micas para obten??o de nanopart?culas de Ag/Y-Al2O3 e Ag/ZnO com propriedades bactericidas". PROGRAMA DE P?S-GRADUA??O EM CI?NCIA E ENGENHARIA DE MATERIAIS, 2017. https://repositorio.ufrn.br/jspui/handle/123456789/23497.

Testo completo

Abstract (sommario):

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2017-06-13T18:57:01Z No. of bitstreams: 1 MichelineDamiaoDiasMoreira_TESE.pdf: 6260721 bytes, checksum: 84aeef87257d33ac9e04bb303022e1cf (MD5)
Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2017-06-14T00:20:11Z (GMT) No. of bitstreams: 1 MichelineDamiaoDiasMoreira_TESE.pdf: 6260721 bytes, checksum: 84aeef87257d33ac9e04bb303022e1cf (MD5)
Made available in DSpace on 2017-06-14T00:20:11Z (GMT). No. of bitstreams: 1 MichelineDamiaoDiasMoreira_TESE.pdf: 6260721 bytes, checksum: 84aeef87257d33ac9e04bb303022e1cf (MD5) Previous issue date: 2017-04-27
A progressiva demanda por ?gua tem feito do tratamento e reutiliza??o de efluentes um tema de relev?ncia mundial. Considerando tal situa??o, v?m sendo realizadas investiga??es acerca do uso de materiais nanom?tricos para obten??o de nanocompostos com propriedades antibacterianas. No sentido de aperfei?oar a obten??o de novos materiais, v?rias metodologias e t?cnicas de prepara??o t?m sido desenvolvidas com o objetivo de controlar a forma e tamanho de part?culas, o que, consequentemente, ir? melhorar e otimizar suas propriedades. Este trabalho consiste na obten??o, caracteriza??o e avalia??o antibacteriol?gica de nanocompostos obtidos pela impregna??o da prata (Ag) na alumina comercial (Y-Al2O3) e no ?xido de zinco (ZnO) a partir de diferentes rotas de s?nteses: m?todo hidrotermal assistido por micro-ondas, sonoqu?mico e associa??o do sonoqu?mico e hidrotermal, destinados a desinfec??o de ?guas residu?rias. Realizou-se um estudo comparativo entre as nanopart?culas Y-Al2O3 e ZnO sintetizada via m?todos sonoqu?mico e hidrotermal por micro-ondas, averiguando a influ?ncia da composi??o e distribui??o do tamanho de part?culas nas propriedades destas. Foram testadas impregna??es de 4%, 8%, 12% e 16% de Ag na Y-Al2O3 e no ZnO. Aplicou-se os nanop?s em efluente proveniente de ETE compacta (Esta??o de tratamento de esgoto), ap?s a etapa do tratamento secund?rio, e em seguida, avaliou-se atrav?s de an?lises bacteriol?gicas, a efici?ncia na remo??o dos indicadores patog?nicos de contamina??o. Os resultados referentes ao emprego do nanocomp?sito ZnO impregnado com 8% de Ag, na propor??o de 0,3g/300mL, por um tempo de contato de 30 minutos, apontaram uma efici?ncia de 99,99% na remo??o de coliformes totais, coliformes termotolerantes e Escherichia coli, alcan?ando padr?es iguais ou superiores ?s t?cnicas j? consagradas de desinfec??o. Os par?metros de rede dos nanocompostos obtidos atrav?s de DRX, juntamente com as t?cnicas de caracteriza??es FRX, an?lise granulom?trica e as micrografias provenientes do MEV/FEG e EDS confirmaram a adequada impregna??o da prata nos ?xidos. Atrav?s da espectrometria de emiss?o ?ptica com plasma- ICP-OES foi revelado que todas as amostras analisadas apresentaram uma quantidade de prata inferior ao limite de detec??o LD<0,50mg/L, atendendo aos teores m?ximos estabelecidos pelas normas vigentes, quanto a toxidade ? sa?de e ao meio ambiente.
The progressive demand for water has made the treatment and reuse of effluents a subject of worldwide relevance. Considering this situation, the use of nanometric materials have been investigated in order to obtain nanocomposites with anti-bacterial properties. In the search for these new materials, several methodologies and preparation techniques have been developed with the purpose of controlling the shapes and the sizes of the particles to, consequently, improve and optimize their properties. This work consists in the achievement, characterization and antibacterial evaluation of nanocomposites obtained by the impregnation of silver (Ag) in commercial alumina (Y-Al2O3) and zinc oxide (ZnO) by different synthesis routes: microwave-assisted hydrothermal method, sonochemical, and an association of sonochemical and hydrothermal methods, intended to the disinfection of wastewater. A comparative study was performed between the Y-Al2O3 and ZnO nanoparticles, synthesized by sonochemical and microwave-assisted hydrothermal methods, investigating the influence of the composition and the distribution of the particle size on the properties of these. Impregnations of 4%, 8%, 12% and 16% of Ag in Y-Al2O3 and in ZnO were tested. The nanoparticles were applied in an effluent coming from a compact WTP (Wastewater Treatment Plant), after the secundary treatment stage, through bacteriological analyzes, and then the efficiency in the removal of pathogenic indicators of contamination was evaluated. The results concerning the use of the ZnO nanocomposite impregnated with 8% Ag, in the ratio of 0,3g/300mL, for a calculated time of 30 minutes, showed an eficiency of 99,99% in the removal of total coliforms, thermotolerant coliforms and Escherichia coli, reaching standards equal or superior to the already established techniques of disinfection. The network parameters of the nanocomposites obtained through XRD, together with the FRX characterization techniques, particle size analysis and the micrographs from the SEM/FEG and EDS confirmed the adequate impregnation of silver in the oxides. The ICP-OES plasma optical emission spectrometry revealed that all the analyzed samples showed a silver quantity below the detection limit LD<0.50 mg/L, complying the maximum levels established by the current standards, regarding the toxicity to health and the environment.

Gli stili APA, Harvard, Vancouver, ISO e altri

14

Sainju, Deepak. "Spectroscopic Ellipsometry Studies of Ag and ZnO Thin Films and Their Interfaces for Thin Film Photovoltaics". University of Toledo / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1430326934.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

15

Souza, Renata Priscilla de Ara?jo. "Estudo das propriedades self-cleaning em substrato t?xtil e magn?ticas do ZnO: Ag nanoestruturado". PROGRAMA DE P?S-GRADUA??O EM CI?NCIA E ENGENHARIA DE MATERIAIS, 2016. https://repositorio.ufrn.br/jspui/handle/123456789/23643.

Testo completo

Abstract (sommario):

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2017-07-17T12:14:30Z No. of bitstreams: 1 RenataPriscillaDeAraujoSouza_TESE.pdf: 4547279 bytes, checksum: 4f04ca670330f1250ce98cf02b59ec9d (MD5)
Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2017-07-17T15:04:44Z (GMT) No. of bitstreams: 1 RenataPriscillaDeAraujoSouza_TESE.pdf: 4547279 bytes, checksum: 4f04ca670330f1250ce98cf02b59ec9d (MD5)
Made available in DSpace on 2017-07-17T15:04:44Z (GMT). No. of bitstreams: 1 RenataPriscillaDeAraujoSouza_TESE.pdf: 4547279 bytes, checksum: 4f04ca670330f1250ce98cf02b59ec9d (MD5) Previous issue date: 2016-08-05
Foram sintetizadas nanoestruturas de ZnO:Ag com nanopart?culas (NPs) de prata a 100 ?C atrav?s de energia micro-ondas com o objetivo de obter um material com propriedades fotocatal?ticas (self-cleaning) em baixos n?veis de energia e magn?ticas. As aplica??es pr?ticas do nanomagnetismo s?o diversas que v?o da geologia, da grava??o magn?tica, at? a medicina. Desse modo, o material foi obtido a partir dos precursores: acetato de zinco di-hidratado e nitrato de prata em diferentes concentra??es tais como ZnO1-x:Agx (x= 0, 0.01 e 0.02). Adicionando a s?ntese polivinilpirrolidona (como agente surfactante) e hexametilenotetramina como agente redutor/agente de precipita??o. Para sua caracteriza??o foram realizadas Difra??es de Raios-X (DRX), Microscopia Eletr?nica de Varredura e por Efeito de Campo (MEV/FEG), Microscopia Eletr?nica de Transmiss?o (TEM), an?lises de ?rea de espec?fica por isortermas Brunauer, Emmett e Taller (BET), Fotoluminesc?ncia (PL) e Espectrofotometria. Os resultados de DRX apontaram principalmente fases cristalinas de Wurtzita para o ZnO e c?bica de face centrada para nanopart?culas de prata met?lica. Atrav?s da espectrofotometria foi poss?vel confirmar por absorb?ncia no comprimento de onda do corante alaranjado de metila a fotocat?lise do ZnO dopado com 1 mol% de prata, sintetizado em 10 min no tempo m?dio de 2 horas e 30 min. Por transmit?ncia foi obtido o gap direto e indireto das composi??es estudadas. Todas as composi??es obtidas apresentaram a propriedade de fotoluminesc?ncia gerada por defeitos estruturais. A dopagem ocasionou para o material puro um deslocamento do verde para o amarelo e o vermelho em consequ?ncia da diminui??o do gap. Apresentou tamb?m pico referente ?s nanopart?culas met?licas de prata em torno de 390 nm. As propriedades magn?ticas foram investigadas atrav?s da an?lise das curvas de magnetiza??o em temperaturas espec?ficas e da magnetiza??o em fun??o da temperatura, obtidas utilizando-se um sistema PPMS. Com estes resultados, foi realizada a etapa de impregna??o das nanopart?culas em poliamida pelo m?todo de deposi??o por imers?o, para isso foi utilizado estireno e acrilato de butila. A caracteriza??o do nanorevestimento foi realizada atrav?s das an?lises de DRX, MEV/EDS, an?lise t?rmica (TG/DTA), Espectroscopia no Infravermelho com Transformada de Fourier (FTIR), Microscopia de For?a At?mica (AFM) e ?ngulo de contato. A avalia??o da propriedade self-cleaning foi baseada na altera??o da cor (?E) usando o espectrofot?metro por reflect?ncia.
ZnO:Ag/Ag nanostructures were synthesized at 100 ?C by microwave energy in order to obtain a material with photocatalytic properties on low energy levels and magnetics. The applications of nanomagnetism are diverse ranging from geology, magnetic recording, to medicine. Thus, the material was obtained from the precursors: zinc acetate dihydrate and silver nitrate (as dopant) in different concentrations such as ZnO1-x:Agx (x= 0, 0.01 e 0.02). Adding polyvinylpyrrolidone synthesis (as surfactant) and hexamethylene as a reducing agent/precipitating agent. For its characterization, the following techniques were performed to evaluate, Diffraction of X-Rays (XRD), Scanning Electron Microscopy and Field Effect (SEM/FEG), Transmission Electron Microscopy (TEM), analysis by isotherms Brunauer surface area Emmett and Taller (BET), Photoluminescence (PL) and Spectrophotometry. The XRD results indicated mainly crystalline phases of wurtzite ZnO for the and for face-centered cubic metallic silver nanoparticles. By undertaking spectrophotometric absorbance it was confirmed by the orange color wavelength methyl photocatalysis ZnO doped with 1 mol% silver synthesized in 10 minutes in an average time of 2 hours and 30 min. Transmittance was obtained with direct and indirect gap of the compositions. All powders obtained showed the photoluminescence property generated by structural defects. The doping of the pure material caused a shift from green to between yellow and red, thus confirming changes in the electrical properties of the same due to decrease in the gap and also showed peak regarding the metal nanoparticles silver around 390 nm. The magnetic properties of the samples were performed using the physical property measurement system (PPMS) from Quantum. Under these conditions the doping improved the photocatalytic property of ZnO. With these prior results, to prove this application the impregnation step was carried out with particles of polyamide by immersion deposition method (dip coating), for this a styrene and butyl acrylate was utilised. The characterization of nano coating ware used using the following techniques: XRD, SEM/EDS, thermal analysis (TG/DTA), Infrared Spectroscopy Fourier Transform (FTIR), atomic force microscopy (AFM) and contact angle. For evaluation of the self-cleaning for photocatalysis property was based on the color change (?E) using the spectrophotometer by reflectance before and after subjecting the samples to ultraviolet radiation for anthocyanins.

Gli stili APA, Harvard, Vancouver, ISO e altri

16

Matsushita, Alan Fernando Yoshiaki. "PREPARAÇÃO E CARACTERIZAÇÃO DE NANOPARTÍCULAS de Ag e ZnO E INCORPORAÇÃO EM FIBRAS DE TECIDOS DE ALGODÃO". UNIVERSIDADE ESTADUAL DE PONTA GROSSA, 2014. http://tede2.uepg.br/jspui/handle/prefix/2128.

Testo completo

Abstract (sommario):

Made available in DSpace on 2017-07-24T19:38:13Z (GMT). No. of bitstreams: 1 Alan Fernando Matsushita.pdf: 4074465 bytes, checksum: 5a6766b6dfd2ff1e7de5f241b872a175 (MD5) Previous issue date: 2014-03-07
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
The fabrics are used for various applications in our daily life, and particularly natural fabrics such as cotton are susceptible to bacterial growth due to moisture that it can accumulate which facilitates this process and also the fibers themselves may serve as nutrients for the growth of microorganisms. In this work, the synthesis of silver and zinc oxide particles was carried out for their and corporation into cotton fibers by the Layer-by-layer method. The silver nanoparticles provide high biocidal activity when incorporated into fabrics textiles and zinc oxide particles promote a block against ultraviolet radiation and also provide the self-cleaning properties for the fabric by the oxidation of compounds on its surface. Therefore the aim of this work was to promote these characteristics in a cotton fabric. The synthesis of silver nanoparticles and zinc oxide were performed using polyelectrolytes as suspension stabilizers. The syntheses were carried out using four ratios related to the metal concentration and polyelectrolyte (1, 2, 5 and 10%). For silver nanoparticles, the 3-n-propylpyridinium silsesquioxane chloride (SiPy+Cl-) was used as stabilizer obtaining nanoparticles of 5 nm in diameter and for ZnO nanoparticles it was used the poly(dialildimethylamonium chloride) PDDA, obtaining in this case particles with sizes larger than 400 nm. These nanocomposites were used to obtain a thin coating on the cotton fibers. For the construction of the films on the cotton fibers, it was used the LbL technique, where it was necessary to perform a prior chemical treatment on the fabric in order to provide an interaction between the cotton fabric surface and the polyelectrolytes. The bilayers were grown in fabrics with the use of polystyrenesulfonate (PSS) as polyanion. Characterization of the fabrics coated with Ag/SiPy+Cl- nanocomposites was performed by varying the number of bilayers. From the SEM images, it was observed the LbL coating on the fabric surface and EDS analysis enabled to estimate the amount of AgNps adsorbed on fabrics. The antibacterial tests for these fabrics showed good results for E. coli and S. aureus bacteria indicating a bactericidal and bacteriostatic character. From the color analysis and UV- Vis spectra of cotton fabrics, it was possible to estimate its homogeneity. Studies of the release of silver nanoparticles were performed by atomic absorption analysis of the washing solution up to 15 washing cycles of the fabric, indicating a high stability of the nanocomposite coating. SEM characterization of the fabrics coated with the nanocomposite ZnO/PDDA showed the growth of the bilayers as well as increase of the ZnO amount on the cotton fiber by the EDS analysis. Through TEM images observed nanoparticles with sizes between 2-10 nm. The analysis of the UV protection factor of these fabrics showed a 60% blockage of UVA and UVB radiations. Studies of photocatalytic degradation of methylene blue dye showed good results degradando totalmente o corante em 8 horas para tecidos revestidos com poucas bicamadas, which increased with the number of bilayers in the fabric. It was observed that in presence of silver nanoparticles, the degradation of the dye becomes more pronounced. The analysis of the shedding of particles of zinc oxide was also performed by atomic absorption analysis of the wash solution until 15 washing cycles. The results for this nanocomposite coated on the fabric also showed satisfactory results.
Os tecidos são utilizados para várias aplicações em nosso dia a dia, e principalmente os tecidos naturais como o algodão são suscetíveis ao crescimento bacteriano devido ao fato de acumularem umidade o que facilita esse processo, além das próprias fibras servirem como nutrientes para o crescimento de microorganismos. Neste trabalho foi realizada a síntese de nanopartículas de prata e óxido de zinco para incorporação em fibras de algodão através do método Layer-by-layer. As nanopartículas de prata conferem alta atividade biocida quando incorporada em tecidos e as nanopartículas de óxido de zinco promovem um bloqueio contra radiação ultra-violeta e também pode tornar o tecido auto limpante através da oxidação de compostos na sua superfície. Portanto o objetivo deste trabalho foi promover essas características em um tecido de algodão. A síntese das nanopartículas de prata e óxido de zinco foram realizadas utilizando-se polieletrólitos como estabilizantes da suspensão. As sínteses foram realizadas em 4 proporções (1, 2, 5 e 10%) do metal em relação a concentração do polieletrólito. Para as nanopartículas de prata utilizou-se o cloreto de 3-n-propilpiridínio silsesquioxano (SiPy+Cl-) como estabilizante obtendo-se nanopartículas de 5 nm de diâmetro enquanto que para o ZnO utilizou-se o Poli(cloreto de dialildimetilamônio) PDDA, obtendo-se neste caso nanopartículas com tamanhos maiores que 400 nm. Esses nanocompósitos foram utilizados para realizar um revestimento sobre fibras de algodão. Para isto utilizou-se a técnica LbL, onde se foi necessário realizar um tratamento químico prévio no tecido para haver uma interação entre a superfície do tecido e os polieletrólitos. As bicamadas foram crescidas no tecido com a utilização do poliestireno sulfonado (PSS) como poliânion. A caracterização dos tecidos revestidos com os nanocompósitos Ag/SiPy+Cl- foi realizada variando-se o número de bicamadas. A partir de imagens de MEV observou-se o revestimento crescido sobre a superfície do tecido e a análise de EDS foi utilizada como tentativa de estimar a quantidade de prata adsorvida nos tecidos. Através de imagens de TEM observou-se nanopartículas com tamanhos entre 2 – 10 nm. Os testes antibacterianos para estes tecidos apresentaram bons resultados para as bactérias E. coli e S. aureus indicando um caráter bactericida e bacteriostático. Também realizou-se a análise de cor através do método CieLab e espectros UV-Vis dos tecidos para estimar a sua homogeneidade. A análise de desprendimento de partículas de prata foi realizada através da análise de absorção atômica da solução de lavagem até um ciclo de 15 lavagens do tecido, resultado que indicou uma alta estabilidade do nanocompósito revestido sobre o tecido. A caracterização dos tecidos revestidos com o nanocompósito ZnO/PDDA foi realizada através das imagens de MEV, onde observou-se o crescimento das bicamadas bem como o aumento da quantidade de ZnO nos tecidos visto pela análise de EDS. A análise do fator de proteção UV destes tecidos apresentou um resultado de até 60% do bloqueio das radiações UVA e UVB. Os testes de degradação fotocatalítica do corante azul de metileno apresentaram bons resultados degradando totalmente o corante em 8 horas para tecidos revestidos com poucas bicamadas, aumentando esse efeito à medida que aumentou-se o número de bicamadas no tecido e na presença de nanopartículas de prata a degradação do corante apresentou-se mais acentuada. A análise de desprendimento de partículas de zinco também foi realizada através da análise de absorção atômica da solução de lavagem até um ciclo de 15 lavagens do tecido, o resultado para este nanocompósito revestido sobre o tecido também apresentou resultados satisfatórios.

Gli stili APA, Harvard, Vancouver, ISO e altri

17

Dias, Hércules Bezerra. "Síntese e caracterização de nanopartículas de ZnO e TiO2 dopadas com Ag para aplicação em materiais dentários". Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/18/18158/tde-14012015-151052/.

Testo completo

Abstract (sommario):

Resinas compostas comumente utilizadas em restaurações, anteriores e posteriores, resultam em maior acúmulo de biofilme bacteriano do que outros materiais restauradores, o que contribui para a formação de cáries secundárias e levam à falha das restaurações. Métodos para inibir a formação do biofilme sobre materiais restauradores dentais vêm sendo estudados há décadas e a inserção de nanopartículas (NPs) representa o que há de mais avançado nos estudos de formulação de materiais dentários antibacterianos. A literatura recente relata que resinas compostas contendo NPs de óxidos metálicos, tais como óxido de zinco (ZnO) e dióxido de titânio (TiO2), têm demonstrado capacidade antibacteriana, contribuindo para o controle do biofilme oral cariogênico. Por outro lado, a inserção dessas NPs pode alterar a cor e as propriedades mecânicas para níveis clínicos inaceitáveis e até mesmo dificultar o processo de fotopolimerização, se inseridas em grandes quantidades. Uma vez que o efeito antibacteriano e as propriedades de resinas compostas modificadas com NPs de óxidos de metais não foram amplamente estudados, esse estudo visou a compreensão destes aspectos, a partir da síntese e caracterização de nanopartículas de ZnO e TiO2 dopados ou não com Ag, inclusão em uma resina composta comercial e análise de propriedades físicas, mecânicas e biológicas do compósito modificado. As sínteses foram realizadas por diversas rotas químicas, resultando em NPs de TiO2 de alta área superficial e NPs de ZnO com morfologia tridimensional, incluindo nanoplates e nanorods que formam estruturas em formato de flores. A modificação da resina composta com NPs de TiO2.Ag alterou drasticamente a resistência à compressão do material, enquanto a adição de NPs de ZnO.Ag manteve a resistência em valores muito próximos ao da resina não modificada. A cor da resina composta sofreu grande alteração quando imergida em solução de café, especialmente após a adição de NPs de ZnO.Ag. A atividade antibacteriana, contra Streptococcus mutans da resina modificada foi considerada significativa, principalmente após a adição de 1 e 2% de NPs de TiO2. A análise dessas propriedades foi importante para o avanço das pesquisas que visam o desenvolvimento de uma resina composta antibacteriana que proporcione estética e propriedades mecânicas adequadas para a confecção de restaurações.
Composite resins used in restorations, anterior and posterior, resulting in greater accumulation of bacterial biofilm than other restorative materials, which contributes to the formation of secondary caries and lead to failure of restorations. Methods for inhibiting biofilm formation on dental restorative materials have been studied for decades and the insertion of nanoparticles (NPs) represents the most advanced in formulation studies of antibacterial dental materials. Recent literature reports that composites containing nanoparticles of metal oxides such as zinc oxide (ZnO) and titanium dioxide (TiO2) have demonstrated antibacterial ability, contributing to the control of oral cariogenic biofilms. On the other hand, NPS inclusion can change the color for unacceptable clinical levels and even hinder the polymerization process, if they are entered as large amounts. Since the antibacterial effect of composite resins modified with nanoparticles of metal oxides has not been widely studied, this study aimed at understanding these aspects, from the synthesis and characterization of nanoparticles of Ag doped and undoped ZnO and TiO2 NPs, inclusion in a composite business and examining their physical, mechanical and biological properties. The synthesis resulted in high surface area TiO2 NPs and three-dimensional ZnO NPs, including nanoplates and nanorods assembled flowers. The modification of the composite with TiO2.Ag NPs changed dramatically the compressive strength of the material, while adding ZnO.Ag NPs maintained compressive strength similar to the unmodified resin. The compostie color stability changed greatly when immersed in a coffee solution, especially after inclusion of ZnO.Ag NPs. The antibacterial activity, against S. mutans, of modified resin was considered significant, especially after addition of 1 and 2% TiO2 NPs. The analysis of these properties is important for the advancement of research aimed at developing an antibacterial composite that provides aesthetic and mechanical properties suitable for dental restorations.

Gli stili APA, Harvard, Vancouver, ISO e altri

18

Santana, Suelanio Viegas de. "Nanopartículas de prata e Ag/Zno nanoestruturado como agentes antimicrobianos obtidos por processo hidrotermal de micro-ondas". Universidade Federal da Paraíba, 2012. http://tede.biblioteca.ufpb.br:8080/handle/tede/7075.

Testo completo

Abstract (sommario):

Made available in DSpace on 2015-05-14T13:21:16Z (GMT). No. of bitstreams: 1 Arquivototal.pdf: 3817465 bytes, checksum: 48db05ac5b1af395dffcbde5a5601151 (MD5) Previous issue date: 2012-08-29
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES
This study consists of the acquisition, characterization and evaluation of antimicrobial silver nanoparticles and nanostructured Ag/ZnO. The silver nanoparticles were obtained through a new route using AgNO3 as precursor salt and ammonium citrate as reducing agent. Concerning the commercial zinc oxide, silver nanoparticles were impregnated using the microwave hydrothermal method at different synthesis times. Samples of Ag / ZnO nanostructured were characterized by using techniques of X-Ray Diffraction (DRX), Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS). The colloidal silver nanoparticles obtained during the processes were characterized through optical spectroscopy in the ultraviolet and visible (UV-Vis) regions. Antimicrobial activity assays were carried for the Ag / ZnO nanostructured and for colloidal silver nanoparticles. They were included six bacteria species as well as six fungal species. Analysis of toxic and cytotoxic activity was performed for colloidal silver nanoparticles on fingerlings of Poecilia Reticulata and Artemia salina. The results show that the chosen synthesis method is effective for silver synthesis, as well as for the process of impregnation of the silver nanoparticles on the commercial zinc oxide. The biological tests revealed significant antimicrobial activity of silver nanoparticles on the micro-organisms analyzed and their low toxicity.
Este trabalho consiste na obtenção, caracterização e avaliação antimicrobiana de nanopartículas de prata e Ag/ZnO nanoestruturado. As nanopartículas de prata foram obtidas através de uma nova rota utilizando AgNO3 como sal precursor e citrato de amônio como agente redutor. Sobre óxido de zinco comercial foram impregnadas nanopartículas de prata por meio do método hidrotermal de micro-ondas em diferentes tempos de síntese. As amostras Ag/ZnO nanoestruturado foram caracterizadas através das técnicas de difração de raios X (DRX), microscopia eletrônica de varredura (MEV) e espectroscopia de energia dispersiva (EDS). As nanopartículas de prata coloidais obtidas durante os processos foram caracterizadas por meio da espectroscopia óptica na região do ultravioleta e visível (UV-Vis). Ensaios de atividade antimicrobiana foram procedidos para o Ag/ZnO nanoestruturado e para as nanopartículas de prata coloidal. Foram incluídas seis espécies bacterianas e seis espécies fúngicas. Análises da atividade tóxica e citotóxica, foram procedidas para as nanopartículas de prata coloidal sobre alevinos de Poecilia Reticulata e sobre Artemia salina. Os resultados demostram que método de síntese escolhido se mostrou eficaz para a síntese da prata, bem como no processo de impregnação das nanopartículas de prata sobre o óxido de zinco comercial. Os testes biológicos revelaram significativa atividade antimicrobiana das nanopartículas de prata sobre os micro-organismos analisados e a sua baixa toxidade.

Gli stili APA, Harvard, Vancouver, ISO e altri

19

Liu, Shuyi [Verfasser]. "Development of Low-Temperature Photon Scanning Probe Microscopy and Nanoscale Characterization of Ultrathin ZnO Layers on Ag(111) / Shuyi Liu". Berlin : Freie Universität Berlin, 2019. http://d-nb.info/1198212047/34.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

20

Andrade, George Ricardo Santana. "Híbridos de ZnO auto-organizado na forma de estrelas e nanopartículas metálicas (Ag, Au) : síntese controlada e avaliação fotocatalítica e antibacteriana". Universidade Federal de Sergipe, 2016. https://ri.ufs.br/handle/riufs/3464.

Testo completo

Abstract (sommario):

Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq
Zinc oxide (ZnO) microparticles with a star-shaped morphology have been synthesized by a novel and simple room-temperature method and decorated with gold (GNP) and silver (SNP) nanoparticles for enhanced photocatalysis and bactericide applications. The presence of thiourea during the precipitation of ZnO in alkaline conditions allowed the control of morphological features (e.g. average size and shape) and the surface functionalization with thiocyanate ions (SCN-). TEM images of the sample prepared at pH 12 suggest that the particles grow according to the oriented attachment mechanism. The emission spectra of these particles showed an interesting feature: the emission band position can be tunable by changing the excitation wavelength. SNPs and GNPs were prepared onto ZnO surface by a photoreduction method and it was found that their sizes can be easily controlled by changing the ZnO/AgNO3 or ZnO/HAuCl4 ratios. The presence of SCN- on the semiconductor surface prevents uncontrollable growth of Ag nanoparticles into different morphologies and high degrees of polydispersity. XRD, SEM, TEM, FTIR, UV-vis-NIR and PL were employed for characterizing the structure, morphology and optical properties of asobtained pure and hybrid nanostructures. Finally, the hybrid ZnO/Ag particles show plasmon-enhanced performance for applications in photocatalysis and antibacterial activity than the pure ZnO counterpart. In this work, it was studied the photodegradation of an aqueous methylene blue solution under UV-A irradiation and antibacterial activity toward 4 bacterial strains, including Gram-positive bacteria Staphylococcus aureus (ATCC 43300, ATCC 25923 and ATCC 33591) and Gram-negative bacteria Pseudomonas aeruginosa (ATCC 27853).
Neste trabalho, micropartículas de óxido de zinco (ZnO) com morfologia de estrela foram preparadas à temperatura ambiente por um método novo e simples e decoradas com nanopartículas de ouro (AuNPs) e prata (AgNPs). A presença de tioureia durante a precipitação do ZnO em meio alcalino permitiu o controle do tamanho e forma e a funcionalização da superfície com íons tiocianato (SCN-). Uma série de imagens de MET da amostra preparada em pH 12 sugere que as partículas crescem de acordo com o mecanismo conhecido como “coalescência orientada”. O espectro de emissão destas partículas mostrou uma característica interessante: a posição da banda de emissão pode ser ajustável alterando o comprimento de onda de excitação. AuNPs e AgNPs foram sintetizadas in situ na superfície do ZnO pelo método da fotorredução, sendo que a simples mudança nas proporções ZnO/AgNO3 ou ZnO/HAuCl4 é capaz de controlar os diâmetros médios das partículas. A presença dos íons SCN- na superfície do semicondutor impede o crescimento incontrolável de nanopartículas de Ag em diferentes morfologias e elevados graus de polidispersidade. DRX, MEV, MET, FTIR, UV-vis-NIR e PL foram utilizados para a caracterização da estrutura, morfologia e as propriedades ópticas de nanoestruturas puras e híbridos. Finalmente, as nanoestruturas híbridas ZnO/Ag apresentaram performance superior para aplicações em fotocatálise e atividade bactericida quando comparadas com o ZnO puro. Neste trabalho, foi estudada a fotodegradação de uma solução aquosa de azul de metileno sob irradiação UVA e a atividade bactericida foi testada para 4 estirpes bacterianas, incluindo as bactérias Gram-positivas Staphylococcus aureus (ATCC 43300, ATCC 25923 e ATCC 33591) e Gram-negativas Pseudomonas aeruginosa (ATCC 27853).

Gli stili APA, Harvard, Vancouver, ISO e altri

21

Khoza, Phindile, e Tebello Nyokong. "Visible light transformation of Rhodamine 6G using tetracarbazole zinc phthalocyanine when embedded in electrospun fibers and in the presence of ZnO and Ag particles". Taylor & Francis Group, 2015. http://hdl.handle.net/10962/d1020251.

Testo completo

Abstract (sommario):

Herein, we report the photocatalytic transformation of Rhodamine 6G (Rh 6G) using tetracarbazole zinc phthalocyanine (TCbZnPc) when alone or when conjugated with ZnO macroparticles (ZnOMPs) and silver nanoparticles (AgNPs), represented as TCbZnPc–ZnOMPs and TCbZnPc–AgNPs, respectively. The photocatalysts were supported onto electrospun polystyrene fibers. The efficiency of TCbZnPc was improved by the presence of both ZnOMPs and AgNPs. HPLC equipped with UV–vis was used to study phototransformation products. The mechanism of transformation was via the N-de-ethylation of Rh 6G.
Original publication is available at http://dx.doi.org/10.1080/00958972.2015.1013944

Gli stili APA, Harvard, Vancouver, ISO e altri

22

Kerivel, Olivier. "Dopage des films minces de ZnO : étude de l’insertion d’Al par spectroscopie d’absorption X et de l’interaction du Mg avec des couches ultra-minces épitaxiées sur Ag(111)". Electronic Thesis or Diss., Sorbonne université, 2023. http://www.theses.fr/2023SORUS543.

Testo completo

Abstract (sommario):

Les films minces de ZnO sont aujourd’hui incontournable dans un grand nombre de domaine, tel que l’optoélectronique, le photovoltaïque, l’électronique flexible et le revêtement vérié, qui exploitent tous son caractère semi-conducteur et sa transparence dans le domaine visible. Dans beaucoup de ces applications, cet oxyde est dopé à l’Al (AZO) pour améliorer sa conductivité sans nuire à sa transmittance. C’est le cas notamment dans l’industrie verrière où l’AZO est utilisé, entre autre, comme couche d’accroche pour d’autres films minces. De ce dopage, peut résulter des problèmes d’adhésion ou de mouillage, en particulier à l’issue de traitements thermiques. Le premier objectif de cette thèse, a été de caractériser l’environnement de l’Al dans la structure würtzite, de couches de ZnO déposées par pulvérisation cathodique. Nous nous sommes intéressé aux effets que pouvaient avoir différentes condition de synthèse : comme le substrat (ZnO , Si ou Silice), le type de cible (métallique ou céramique), la concentration en Al, ou encore l’atmosphère de dépôts (avec ou sans oxygène). De plus, nous avons étudié les modifications que des recuits, haute température (800°C) réalisés en atmosphère oxydante (à l’air) ou réductrice (sous ultra-vide), pourraient entrainer sur la position ou l’environnement de l’Al au sein de ces couches. Pour répondre à ces question, nous avons eu recours aux techniques de caractérisation classique de couches mince (XPS, STM, LEED, AFM et XRD), ainsi qu’à des mesures sur grand instruments. Il a récemment été démontré qu’une couche suffisamment mince de ZnO (de l’ordre de quelques monocouches) déposée, sur substrat cristallin de maille hexagonale, comme l’Ag (111) ou le Pt (111), pouvait adopter une conformation pseudo graphitique (dite également de type h-BN). Le mécanisme de formation de cette nouvelle structure cristallographique, n’est pas encore totalement compris, mais elle pourrait présenter des propriétés inédite pour le ZnO. Ainsi, dans le second volet de cette thèse, nous nous sommes concentré sur le dépôt par évaporation réactive de couches ultra-minces de ZnO sur substrat d’Ag(111), afin de reproduire les résultats de la littérature et explorer les conditions de synthèse de ces films sub-nanométriques. Par la suite, nous avons explorer les possibilité de dopage de ces couches par le Mg, qui est un matériau couramment adjoins au ZnO dans le but de modifier ses propriétés électroniques. Nous avons donc chercher à comprendre l’influence que pouvait avoir l’ajout de Mg sur cette nouvelle structure
ZnO thin films are now indispensable in many fields, such as optoelectronics, photovoltaics, flexible electronics, and transparent coatings, all of which exploit its semiconductor properties and transparency in the visible range. In many of these applications, this oxide is doped with Al (AZO) to improve its conductivity without affecting its transmittance. This is particularly the case in the glass industry, where AZO is used, among other things, as an adhesion layer for other thin films. However, this doping can result in adhesion or wetting issues, especially after heat treatments. The first objective of this thesis was to characterize the environment of Al in the wurtzite structure of ZnO films deposited by cathodic sputtering. We investigated the effects of different synthesis conditions, such as the substrate (ZnO, Si, or silica), the type of target (metallic or ceramic), the Al concentration, and the deposition atmosphere (with or without oxygen). Additionally, we studied the modifications that high-temperature annealing (800°C) in oxidizing (air) or reducing (ultra-high vacuum) atmospheres could induce on the position or environment of Al within these films. To answer these questions, we employed standard characterization techniques for thin films (XPS, STM, LEED, AFM, and XRD), as well as measurements on large instruments. It has recently been demonstrated that a sufficiently thin layer of ZnO (on the order of a few monolayers) deposited on a hexagonal lattice crystalline substrate, such as Ag(111) or Pt(111), can adopt a pseudo-graphitic conformation (also known as h-BN type). The mechanism of formation of this new crystallographic structure is not yet fully understood, but it could present unprecedented properties for ZnO. Thus, in the second part of this thesis, we focused on the reactive evaporation deposition of ultra-thin ZnO films on Ag(111) substrates to replicate the results reported in the literature and explore the synthesis conditions of these sub-nanometric films. Subsequently, we explored the possibilities of doping these films with Mg, which is commonly added to ZnO to modify its electronic properties. Therefore, we sought to understand the influence of adding Mg on this new structure

Gli stili APA, Harvard, Vancouver, ISO e altri

23

Chung, Hsin-Yi, e 鍾心怡. "Preparation and Characterization of Heterogeneous Ag/ZnO". Thesis, 2009. http://ndltd.ncl.edu.tw/handle/40561869273860080918.

Testo completo

Abstract (sommario):

碩士
國立高雄應用科技大學
化學工程與材料工程系
97
Ag/ZnO nanomaterials were synthesized by three different processes in this study. The Ag-deposited ZnO obtaining from process A were prepared by mixing Zn(NO3)2•6H2O and hexamethylenetetramine (HMT) at a mole ratio of 2:1 as well as AgNO3. The process B first prepared ZnO by reacting with Zn(NO3)2•6H2O and HMT at a mole ratio of 2:1; then, The Ag-deposited ZnO rods were formed by adding AgNO3 to the ZnO suspension. The Ag/ZnO heterostructures obtaining from process C were first prepared ZnO nanoparticles by heating Zn(CH3COO)2•2H2O at 65C and pH 13 in the presence of methanol, followed by reacting with AgNO3. The Ag-deposited ZnO preparing by process A were the ZnO rods with a diameter around 100 nm (aspect ratio of 5:1) loaded with the Ag nanopartitcles with a diameter around 50 nm. The diameter of the Ag-deposited ZnO rods forming in process B were about 200 nm, which were loaded with the Ag nanoparticles (20-30 nm in diameter). The Ag/ZnO heterostructures from process C were the Ag nanoparticels (20-30 nm in diameter) dispersing in the ZnO nanoparticles (30 nm in diameter). The XRD and TEM analysis showed that silver oxide was not observed. There was no bonding between ZnO and Ag; namely, Ag nanoparticles were deposited on the surfaces of ZnO rods or nanoparticles. Photocatalysis experiments (irradiated by 365 nm) showed that the photocatalytic activity of the Ag/ZnO prepared from process C was better than the products from process A and B. It can be expected that the specific surface area is one of the critical factors affecting the photocatalytic activity. In addition, the photocatalytic activity of Ag/ZnO was significant higher than ZnO, indicating that the photogenerated elections could be captured by Ag, which decreased the recombinantion of electron-hole pairs and improved the photocatalytic acitivty. Additionally, the UV/visible spectrophotometer observation demonstrated that the ZnO nanoparticles preparing by process C were transparent in visible light and were capable of absorbing UV. It can be seen that the ZnO nanoparticles from process C is a promising agent for sunscreen.

Gli stili APA, Harvard, Vancouver, ISO e altri

24

Cheng, Chun-Han, e 程俊翰. "Study on High Conductive and Transparent Ag/ZnO". Thesis, 2014. http://ndltd.ncl.edu.tw/handle/vqbxg9.

Testo completo

Abstract (sommario):

碩士
國立虎尾科技大學
光電與材料科技研究所
102
In this article, we have reported on the low-temperature-grown zinc oxide (ZnO) grown by dual-plasma-enhanced metal organic chemical vapor deposition (DPEMOCVD) facility. The ZnO grown on sapphire at 185 oC . A transmittance of 87 %, and resistivity of 6.94 Ωcm. Then deposition of silver nanoparticles on top of the zinc oxide thin films by liquid phase deposition. Analysis of different concentrations of silver nitrate and sodium hydroxide, different deposition time, different annealing temperatures, different annealing time. The optimum concentration of 0.12M silver nitrate and an annealing temperature 500 oC and six minute . A transmittance of 82 % and resistivity of 2.74×10-3 Ωcm, the film coefficient 1.30×10-5Ω-1. The XRD analysis of the growth of Ag/ZnO film has a (002) peak of the silver (111) peak. Silver reduction using sodium hydroxide can accelerate the reaction rate, the optimal concentration of 0.025M sodium hydroxide at 500 oC annealing temperature and six minute, the resistivity can reach 6.98×10-4 Ωcm, and transmittance of 80.7%. Finally, we apply the Ag/ZnO thin film to InGaN/GaN light-emitting diode as the transparent conductive layer (TCL). As compared to the InGaN/GaN LEDs with indium-tin-oxide (ITO) TCL, the InGaN/GaN LEDs with Ag/ZnO thin film present the same optical and electrical characteristics, indicating that the Ag/ZnO thin film grown by DPEMOCVD system can be a candidate for TCL in InGaN/GaN LEDs. Keywords:DPEMOCVD; Liquid phase deposition; Ag/ZnO

Gli stili APA, Harvard, Vancouver, ISO e altri

25

Rakgalakane, Ben Pesana. "Aqueous synthesis and characterization of CdSe/ZnO and Ag/ZnO core/shell nanomaterials". Thesis, 2012. http://hdl.handle.net/10210/5323.

Testo completo

Abstract (sommario):

M.Sc.
This dissertation describes the synthesis and characterization of CdSe/ZnO and Ag/ZnO core/shell nanoparticles using water as a solvent. The effects of the concentration of the shell precursor, pH, and stabilizing agents on the properties of the nanoparticles were investigated. In general, the type of capping agents had an influence on the crystallite size of the core nanocrystals. The particle size distributions which were calculated from TEM images show that thioglycolic acid as a capping agent produced larger particle sizes compared to thioglycerol. For example, thioglycolic acid produced on average 5.0 nm CdSe nanoparticles while 4.0 nm average CdSe particle size was obtained when using thioglycerol as stabilizer. This observation was confirmed by UV/Vis absorption results which showed that thioglycerol capped CdSe NCs exhibited excitonic peaks positioned at lower wavelength than thioglycolic capped CdSe NCs. XRD results showed that the capping agents used in the current work had no influence upon crystal structure of the CdSe nanocrystals as the cubic structure was obtained with both stabilizers. The effect of shell precursor concentration at pH 12 showed heterogeneous formation of ZnO nanoparticles at high shell precursor concentrations. Various ZnO morphologies including nanoflowers and nanotriangles were observed on TEM images when 50 mL and 25 mL of zinc nitrate solution were used as shell precursors. UV/Vis absorption results also confirmed the presence of ZnO absorption peaks for samples prepared with 50 mL and 25 mL of zinc nitrate solution as shell precursors. PL results showed an increase in peak intensity as a function of precursor volumes. XRD results showed diffraction patterns due to the wurtzite structure of ZnO. CdSe diffraction patterns in these samples were not detected by the XRD instrument. At low volume of the shell precursor, which was 5 mL of 0.05 M zinc nitrate, TEM results showed that spherical CdSe/ZnO core/shell nanoparticles were obtained at pH 12 with 5 mL of 0.05 M zinc nitrate solution and 0.1 M sodium hydroxide used as shell precursor solutions, and thioglycerol as a stabilizer. XRD analysis of the v sample exhibited ZnO diffraction patterns and the CdSe patterns were not detected owing to their low peak intensities compared to those of the ZnO. Similar results were obtained when thioglycolic acid was used a stabilizing agent. However, TEM images showed the hexagonal shape of the CdSe/ZnO core/shell nanoparticles. The pH level was found to influence the photoluminescence properties of the CdSe/ZnO core/shell nanoparticles. The enhanced PL intensity was obtained with CdSe/ZnO core/shell nanoparticles with pH 9 in comparison with CdSe/ZnO core/shell nanoparticles prepared at pH 12. TEM images showed the presence of a thin ZnO shell on the surface of CdSe cores for CdSe/ZnO prepared at pH 9 which could be attributed to the PL enhancement. Although EDS results confirmed the presence of elements such as Cd, Se, Zn and O for both the CdSe core and ZnO shell, the XRD results confirmed the presence of only CdSe diffraction patterns, which suggested the ZnO shell had low peak intensity or was amorphous. A similar effect of these capping agents was observed for Ag nanoparticles as thioglycerol produced average particle size of 16.0 nm whereas 31.0 nm as the average particle size was obtained with thioglycolic acid as stabilizing agent. The crystal phase of Ag NPs was independent of the type of stabilizer. The Ag NPs precipitated in face centred cubic phase. Core/shell Ag/ZnO nanoparticles were produced with 5 ml of zinc nitrate as shell precursor. Higher volumes (50 ml and 25 ml) of zinc nitrate shell precursor induced heterogeneous precipitation of ZnO nanoparticles. XRD patterns confirmed peaks due to ZnO and Ag for Ag/ZnO core/shell nanoparticles.

Gli stili APA, Harvard, Vancouver, ISO e altri

26

Qian, Dong-Wei, e 錢東緯. "Improving photocatalytic ability of ZnO by coupling with Ag". Thesis, 2012. http://ndltd.ncl.edu.tw/handle/67759431365146303580.

Testo completo

Abstract (sommario):

碩士
淡江大學
化學工程與材料工程學系碩士班
100
The ZnO and Ag-coupled ZnO (Ag/ZnO) photocatalytic particles were synthesized using a polyol process and/or a photochemical reduction technique. Effects of Ag contents and calcination temperature on characteristics and photocatalytic abilities of the ZnO and Ag/ZnO particles were investigated using thermal analysis, x-ray diffraction, infrared spectroscopy, diffusion-reflectance spectroscopy, BET specific surface area measurement, scanning electronic microscopy, transmission electronic microscopy and photocatalytic reaction test system. The properties and photocatalytic abilities of the obtained ZnO and Ag/ZnO particles were also compared with those of a commercial photocatalyst TiO2 (P25, Degussa, Germany). The ZnO powders were prepared using the polyol method, followed by calcining at different temperatures. While increasing the calcination temperature increased the average crystallite sizes and the degree of agglomeration of the ZnO particles, the specific surface area decreased with increasing the calcination temperature. By photocatalytically decomposing the methylene blue in water under the irradiation of 365-nm ultraviolet light, it was found that the ZnO calcined at 500oC exhibited better photocatalytic performance than the ZnO calcined at other temperatures and the P25. The Ag/ZnO particles were prepared by photochemically reducing Ag+ to metallic Ag on the surface of the calcined ZnO particles. Ag loaded on the surface of ZnO particles can trap the light-excited electrons from the ZnO and retard the electron-electron hole recombination rate, which should result in enhancement of photocatalytic abilities of the ZnO. It is found that the ZnO calcined at higher temperature can have more Ag nanoparticles loaded on the surface of ZnO particles. Regardless the calcination temperature used, the Ag/ZnO particles possessed better photocatalytic abilities than the ZnO particles and the P25. For photocatalytically decomposing the methylene blue in water under 365-nm ultraviolet light irradiation, the Ag/ZnO prepared using the ZnO calcined at 600oC and a Ag/ZnO molar ratio of 0.045 had a reaction rate constant (based on the mass of the photocatalyst used) km = 1.93m3/(kg‧min), which was about 4.9 times of that of the Degussa-P25 (km = 0.39 m3/(kg‧min)).

Gli stili APA, Harvard, Vancouver, ISO e altri

27

Liu, Fang-Cheng, e 劉芳成. "A Study on the ZnO-based Homojunction and ZnO/GaN Heterojunction Diodes with p-type Ag-ZnO Cosputtered film". Thesis, 2018. http://ndltd.ncl.edu.tw/handle/645829.

Testo completo

Abstract (sommario):

碩士
國立虎尾科技大學
光電工程系光電與材料科技碩士班
106
In study,Ag dope ZnO films were prepared by RF magnetron co-sputtering system by p-type film, the heat treatment undoped ZnO film is activated, Changing the intermediate activation layer, adding barrier layer AlN-ZnO film double hetero-junction, improving the electronic hole limitation ability of the film, and adding aluminum nitride boundary layer to increase the ability of electronic limitation, so that the benefit of luminescence will be changed, is hall measurement of electrical properties and photoluminescence spectra to understand film stacking characteristics, the electrical characteristics can be found that the Ag dopede ZnO has a p-type conductive pattern. the double hetero-junction and the undoped ZnO film in the intermediate layer film show n-type conductive pattern, the photoluminescence spectra show that middle layer AlN-ZnO film double hetero-junction of the middle layer effectively inhibits the oxygen vacancy in the ZnO and increases the intensity of the luminescence in the short wavelength part, and the intensity of the short wavelength luminescence is obviously enhanced by the addition of the aluminum nitride layer.This study is made p-ZnO/n-ZnO、p-ZnO/DH/n-ZnO and p-ZnO/AlN/DH/n-ZnO homo- junction diode in sapphire substrate, In current-voltage characteristics, in middle layer AlN-ZnO film double hetero-junction, when the voltage is positive or negative 0.68V ,the current ratio is about 2.21, or confined aluminum nitride layer, when the voltage is positive or negative 1.15V ,the current ratio is about 5.59, Both have rectifying characteristics. Further study is made on the different bottom film n-GaN and p-GaN thin films as heterostructures, the n-GaN film is made for the structure bottom p-ZnO/n -GaN、p-ZnO/DH/ n-GaN and p-ZnO/AlN/DH/ n-GaN hetero-junction diode, it n-Gan crystal structure and electrical characteristics better than those of n-ZnO, In current-voltage characteristics, Both have very rectifying characteristics, study the p-Gan film is made for the structure bottom p-ZnO/p -GaN、p-ZnO/DH/ p-GaN and p-ZnO/AlN/DH/ p-GaN hetero-junction diode, from the electrical excitation spectrum and the band diagram, under voltage, the p-GaN film can provide a few holes to increase the electron hole recombination chance to produce luminescence, the addition of aluminum nitride confining layer prevents electrons from being confined to the activation layer of the intermediate layer, which enhances the single photoluminescence.

Gli stili APA, Harvard, Vancouver, ISO e altri

28

Hung, Pei-Shan, e 洪珮珊. "Impacts of ZnO, Ag, Fe Nanoparticles on Biological Phosphorus Removals". Thesis, 2013. http://ndltd.ncl.edu.tw/handle/85327544200027917677.

Testo completo

Abstract (sommario):

碩士
國立暨南國際大學
土木工程學系
101
This study explored the impacts of ZnO, Ag, Fe nanoparticles on biological phosphorus removal. Experimental results showed that the phosphorus removal ability of phosphorus accumulating organism (PAO) was completely inhibited when ZnO nanoparticle concentration was 2 mgl-1. Only 7% removal ability remained when Ag nanoparticle concentration was 10 mgl-1. The phosphorus removal ability of PAO was initially inhibited at 100 mgl-1 concentration of Fe nanoparticle Statistical analysis showed that the three kinds of nanoparticles significantly affected the PAO’s metabolisms, including phosphorus uptake, PHA synthesis/degradation, and glycogen degradation/synthesis. The influence of nanoparticles was greater at aerobic phase than at anaerobic phase. The order of the inhibition degree of nanoparticles for PAO was ZnO>Ag>Fe3O4. This study also found that the influence of nanoparticles on PAO’s metabolisms mainly resulted from the release of ionic metals and the formation of reactive oxidation species (ROS). The concentration of ionic metals and ROS increased with increasing nanoparticle concentration.

Gli stili APA, Harvard, Vancouver, ISO e altri

29

Ya-ChiKo e 柯雅淇. "Preparation and application of Ag/ZnO/reduced graphene oxide nanocomposite". Thesis, 2015. http://ndltd.ncl.edu.tw/handle/03458305987687493846.

Testo completo

Abstract (sommario):

碩士
國立成功大學
化學工程學系
103
In this study, Ag/ZnO/reduced graphene oxide (Ag/ZnO/rGO) nanocomposite was fabricated and its applications in the detection and killing of bacteria were investigated. This nanocomposite combined the photocatalytic property of ZnO nanoparticles, the high specific surface area and near infrared (NIR) photothermal conversion property of rGO, and the bacteria-killing capability and surface enhanced Raman scattering (SERS) property of Ag nanoparticles. At first, ZnO/rGO nanocomposite was prepared from zinc acetate and graphene oxide (GO) by solvothermal method in the mixture of ethylene glycol and NaOH aqueous solution. The influences of GO content on the growth of ZnO nanoparticles on the surface of rGO and the photocatalytic property were examined to obtain a ZnO/rGO nanocomposite with better photocatalytic activity. Secondly, in the silver nitrate-containing arginine solution, Ag nanoparticles were deposited on the surface of ZnO/rGO nanocomposite by microwave-assisted method. It was demonstrated that the resulting Ag/ZnO/rGO nanocomposite not only could be successfully used as the SERS substrate for the detection of E-Coli, but also could be used for the efficient killing of E-Coli in the dark and under the full Xe lamp or NIR irradiation via the Ag nanoparticles-related and photocatalytic or photothermal killing mechanisms. The full Xe lamp irradiation led to the best bacteria-killing efficiency and the second best one was observed under NIR irradiation. This revealed that the Ag/ZnO/rGO nanocomposite could provide more ways and better performance for killing bacteria as compared to the individual Ag nanoparticles. Accordingly, the Ag/ZnO/rGO nanocomposite developed in this study indeed possessed both the bacteria detection and killing properties.

Gli stili APA, Harvard, Vancouver, ISO e altri

30

Hsu, An-di, e 許安迪. "The study of ZnO nanowires with Ag nanoparticles byhydrothermal method". Thesis, 2010. http://ndltd.ncl.edu.tw/handle/25041335149645490967.

Testo completo

Abstract (sommario):

碩士
國立臺南大學
電機工程研究所
98
In this paper, the ZnO and silver nanoparticles - ZnO nanowires were prepared on the glass substrates by hydrothermal method and were used to make the ultraviolet photodetector and gas sensor. We used the zinc nitrate hexhydrate (Zn (NO3)2. 6H2O) 、 hexamethylenetetramine (C6H12N4) and silver nitrate (AgNO3) to synthesize the silver nanoparticles - ZnO nanowires, without the silver nitrate in front of the three precursor solution namely was the part of no silver nanoparticles. The ZnO nanowires and silver nanoparticles - ZnO nanowires would be analyzed by SEM, XRD and PL equipment. From the SEM image, it can be see that a lot of Ag particles capped on the top of the ZnO nanowires. For the part of the ultraviolet photodetector, from the photoresponse image, the photoresponse time of the silver nanoparticles - ZnO nanowires is faster to saturate than the ZnO nanowires. For the part of the gas sensor, the ZnO nanowires and silver nanoparticles - ZnO nanowires would be annealed at 300℃ for two hours in the air first, and made a gas sensor to sense ethanol gas at the temperature of 300° after. From the sensitivity, the sensitivity of the silver nanoparticles - ZnO nanowires was three to four times higher than the ZnO nanowires.

Gli stili APA, Harvard, Vancouver, ISO e altri

31

Kao, Wei-tsung, e 高維聰. "Photocatalyst and Characterization of ZnO and Ag-doped ZnO Nanowires Synthesized by Ultraviolet-light Decomposition Process". Thesis, 2012. http://ndltd.ncl.edu.tw/handle/58581445556709207513.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

32

Chang, Yu-Wei, e 張育瑋. "Study of low resistance and high transmittance of ZnO/Ag/ZnO transparent conductive oxide thin film". Thesis, 2011. http://ndltd.ncl.edu.tw/handle/02696129056944953331.

Testo completo

Abstract (sommario):

碩士
明新科技大學
化學工程與材料科技系
99
Transparent conductive oxide film shows high transmittance in the visible region, and low conductivity, But, a single layer of transparent conductive oxide can not achieve a satisfactory resistivity. There are several approach to reach this tragets. One of them, by inserting a thin low resistivity metal layer into the matrix of transparent conductive oxide. The multilayers have enough visible transmittance and low resistivity. In this thesis, an indium-free zinc oxide /silver/zinc oxide stack layer (ZAZ) on the glass with high conductivity and high transmittance were investigated through physical vapor deposition. Some samples are annealed to improve their materials properties. The crystallinity,, electrical performance and optical properties were studied. X-ray diffraction analysis of ZnO and Ag by PVD reveals the strong (0002) and (111) preferred orientation diffraction peak, respectively. In the case of ZnO(25 nm)/Ag(10 nm)/ZnO(25 nm), the micrograph revealed by transmission electron microscopy analysis shows that the 10-nm-thick silver layer is a continuous film. Silver and zinc oxide thin film interface were clear, suggests that the interfaical reaction between ZnO and Ag did not occur. Post-deposition annealing treatment was used to improve the transprancy of the stack layer without significally increasing resistance, the morphology change of Ag layer and silver and the increasing grain size of ZnO are responsible for this result. With annealing temperatures higher than 200 ℃ the surface roughness of the sandwiched structure also increases, Figure of merit can be used to analyze the ZnO/Ag/ZnO multilayers after the post-deposition annealing treatment, it also is a good evaluation for a transparent conductive coating as a electrode. ZnO/Ag/ZnO multilayer films after annealing at 200 ℃ for 20 minutes show a FOM value of 5×10-2 Ω-1. ZnO/Ag/ZnO can meet the requirement of the low resistance and high transmittance for a transparent conductive electrode in the related electronic and optical application.

Gli stili APA, Harvard, Vancouver, ISO e altri

33

Yu-Chen, Yen, e 陳彥友. "Multifunctional Polyacrylonitrile-ZnO/Ag Electrospun Fiber Membranes: Various ZnO Morphologies for Photocatalytic, UV-shielding, and Antibacterial Applications". Thesis, 2014. http://ndltd.ncl.edu.tw/handle/83814956739342519329.

Testo completo

Abstract (sommario):

碩士
國立臺北科技大學
有機高分子研究所
102
In this study, we firstly prepared polyacrylonitrile (PAN)-ZnO/Ag composite ES fiber membranes consisting of pineal-type, flower-type, and sea-urchin-type ZnO morphologies by using ES technique, hydrothermal synthesis, and Ag reduction. The effects of the various ZnO structures on the fiber morphologies, photocatalytic efficiency, UV protection, and mechanical properties as well as how the additive Ag enhanced antimicrobial activity. Our results indicated that the photocatalytic and UV-protection efficiency of PAN-ZnO/Ag ES fiber membranes can be altered by varying the morphology of ZnO. The various ZnO architectures exhibited differences in photocatalytic activity and UV-shielding efficiency, and were ranked as follows: sea-urchin > flower- > pineal-type. Sea-urchin-type ZnO features higher surface-to-volume ratio than other architectures do because of its distinctive structure, thus yielding higher performance. The present study demonstrated that self-standing PAN-ZnO/Ag composite fiber membranes, especially those with the sea-urchin-type ZnO structure, can be applied in multifunctional textiles such as water purification filters and antibacterial and UV-shielding clothes.

Gli stili APA, Harvard, Vancouver, ISO e altri

34

Li-Yi, Tsai, e 蔡禮義. "Photocatalyst and Characterization of ZnO and Ag-doped ZnO Nanorods Synthesized by Oil-bath Thermal Decomposition Process". Thesis, 2014. http://ndltd.ncl.edu.tw/handle/45394328827330268220.

Testo completo

Abstract (sommario):

碩士
逢甲大學
材料科學與工程學系
102
In this study, ZnO (Znic oxide) nanorods have been synthesized using chemical solution reaction method, oil bath, which is low cost and short process time (only require five minutes). For commercial application this have development potential. As-synthesized ZnO nanorods have been addressed to characterize the photocatalytic. Zinc acetylacetonate hydrate (Zn(AcAc)2) was acted as a solute while denatured ethanol and deionized water were used as solvent to prepare the Zn(AcAc)2 precursors. Using Zn(AcAc)2 precursors into the round-bottomed beaker with 200 ℃ silicone oil to synthesize the ZnO nanrods. In addition, we used MOD-Ag as a doping source to synthesize Ag-doped ZnO nanostructures. By thermal decomposition, using oil bath to synthesize the ZnO nanrods, which are wurzite structures with hexagonal cylinder. And ZnO nanorods have Oriented attachment of self-assembly behavior growing mode. By Photoluminescence and X-ray photoelectron spectroscopy analysis, the ZnO nanorods are a kind of deficient photocatalyst. In this study, find out the ZnO nanorods have maximum concentration of double electric oxygen vacancies by thermal decomposition in five minutes. And indirectly caused a lot of hydroxyl radicals. Via photocatalytic degradation methyl orange experiment, it have the most excellent of the degradation efficiency and catalytic effect than commercial TiO2 Degussa P25. In this study, we find out a way which is low production cost, process time is short, the growth temperature is low, suitable for mass production, to synthesize the ZnO nanrods. And have great potential for development in the application of ZnO photocatalyst and other related industries.

Gli stili APA, Harvard, Vancouver, ISO e altri

35

Chiu, Hsu-Feng, e 邱旭鋒. "Self-Assembled Ag Particles on Si0.8Ge0.2 and Growth of ZnO Nanowires". Thesis, 2004. http://ndltd.ncl.edu.tw/handle/52300959224410792897.

Testo completo

Abstract (sommario):

碩士
國立清華大學
材料科學工程學系
92
Abstract Self-assembled Ag particles on Si0.8Ge0.2 and the growth of ZnO nanowires have been investigated. Self-assembled method is utilized for the formation of surface structure of Ag nanoparticles on Si0.8Ge0.2. The surface reaction was induced in a furnace with N2 flowing. The resulting surface structure of Ag on SiGe was characterized by scanning electron microscopy (SEM), energy dispersion spectrometer (EDS), and transmission electron microscopy (TEM). Ag atoms were observed to segregate to the node points of the honeycomb structure after annealing at 800 °C for 90 min. It was found that the Ag particles gradually sank into SiGe substrate. Small particles were found to permeate faster than large particles. Cross-sectional TEM image showed that there is an oxide film covering Ag particles. Small particles are sometimes embedded in the oxide layer. The observation indicated that Ag did not react with SiGe to form compounds. The formation of an oxide layer was found to stabilize the Ag particles. The growth of ZnO nanowires was found to depend on the catalysis of Au particles. Factors such as ZnO/C ratio, temperature, growth time, pressure of O2, amount of Zn vapor and catalyst, have been varied to investigate their effects on the growth. The resulting nanowires were characterized by SEM, TEM, and high-resolution transmission electron microscopy (HRTEM). The quantity of ZnO and C affects the concentration of Zn vapor to grow. A high concentration of Zn leads to faster growth. The nanowires were grown via a vapor-liquid-solid growth mechanism. ZnO nanowires grew in length with holding time. For low gas flow, the nanowires were grown under low supersaturation. For samples prepared with ZnO/C ratio equaling 1 (3.33 g ZnO and 0.5 g C), the temperature 690 °C, holding time 90 min, a constant flow of Ar (25 sccm) and O2 (5 sccm), P equaling 1.5 Torr, with deposited Au as catalyst, ZnO nanodrills were grown on the substrate. The nanodrills are about 10 to 150 nm in average diameter and 1 to 2 micrometers in length. From the HRTEM image of ZnO nanodrills, core-shell structure is evident in the sample. The core and shell were found to be ZnO and Zn. No amorphous material is present at the interface. The results clearly showed that the concentration of Zn affects the growth rate to produce different kinds of ZnO nanowires.

Gli stili APA, Harvard, Vancouver, ISO e altri

36

Wei-KangHsieh e 謝濰岡. "Investigation of thermal treatment for ZnO photodetector with Ag nano-interlayer". Thesis, 2012. http://ndltd.ncl.edu.tw/handle/97922299881154848416.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

37

Tu, Tsung-Hsien, e 凃宗賢. "A study on the Ag/n-ZnO thin film Schottky diode". Thesis, 2012. http://ndltd.ncl.edu.tw/handle/91343592370066964362.

Testo completo

Abstract (sommario):

碩士
崑山科技大學
光電工程研究所
100
The preparation of sol-gelprocessed zinc oxide (ZnO) thin film and ZnO based Schottky were proposed in the thesis.The ZnO thin film was deposited on Si substrate and annealed by rapid thermal annealing at 800℃ for 45 sec.The electrodes of the Schottky diode was deposited silver by thermal evaporation and then were annealed by RTA at 200 and 350℃, respectively.The Schottky diode shows a barrier height of 0.84 eV with an ideality factor of 1.74 and a reverse leakage current of 0.12 mA after was annealed at 350℃. In addition,the Norde model and Cheung''s equation,were also used to discuss the barrier height and series resistance effects.For the temperature dependent current-voltage characteristics, the Schottky diode shows a increase of barrier height and a decrease of ideality factor as the measured temperature increased. The barrier inhomogeneous effect it was also discussed through Gauss distribution model in the temperature dependent effects.

Gli stili APA, Harvard, Vancouver, ISO e altri

38

CHU, YEN-LIN, e 朱彥霖. "Study for the Gas Sensors Based on Ag-doped ZnO Nanosheets". Thesis, 2018. http://ndltd.ncl.edu.tw/handle/s2mb7y.

Testo completo

Abstract (sommario):

碩士
國立虎尾科技大學
光電工程系光電與材料科技碩士班
106
In this study, the zinc oxide (ZnO) nanosheets produce gas sensors were investigated. By using the hydrothermal method, the Ag-doped zinc oxide nanosheets were synthesized, explored to produce stable and good characteristics of gas sensors. There are two sections of study are as follows. The first section : The zinc oxide films as seed layers were deposited on glass substrates by radio frequency magnetron sputtering (RF-sputtering) technique. The zinc nitrate (Zn(NO3)2‧6H2O), hexamethylenetetramine (HMTA) and different concentrations of silver nitrate (AgNO3) were added into the solution. The growth of different nanostructures was with different container, temperature, and time. It was to reduce the lattice mismatch and so on by rapid thermal annealing (RTA) process, High Resolution Scanning Electron Microscope (HR-SEM), Energy Dispersive Spectrometer (EDS), X-Ray Diffractometer (XRD), UV/Visible light Spectrophotometer (UV/Visible), Photoluminescence spectrum (PL), and High Resolution Analytical Electron Microscope (HR-AEM) were then to determine the morphology, composition, lattice, optics, and so on of the Ag-doped zinc oxide nanostructures. Additionally, it is to explore the better characteristics of concentration. The second section : It is to define the growth areas by yellow photolithography technology. The zinc oxide films as seed layers were deposited on silicon substrates by radio frequency magnetron sputtering (RF-sputtering) technique. The one dimensional (1D) nanostructures were fabricated by hydrothermal method under better characteristics of growth conditions. Enhance the responsivity of gas sensors by the ratio of length/width and a large area of gas adsorption conditions in one dimensional nanostructures. In the study, the concentration of zinc nitrate (0.06 M) and hexamethylenetetramine (0.06 M) was added into the solution. The results show that the growth time of Ag-doped (0.002 M) zinc oxide nanosheets is 6 hours under 120 oC would be optimization. Meanwhile, in 200 oC gas measurement temperature, the 80 % responsivity of NO gas significantly excellence, respectively. This also indicated that the doping Ag would be more effect in gas devices.

Gli stili APA, Harvard, Vancouver, ISO e altri

39

Li, You-He, e 李佑禾. "An Investigation on Ag-ZnO Films and Fabrication on Homojunction Diode". Thesis, 2017. http://ndltd.ncl.edu.tw/handle/as742s.

Testo completo

Abstract (sommario):

碩士
國立虎尾科技大學
光電工程系光電與材料科技碩士班
105
In study,Ag dope ZnO films and undoped ZnO films were prepared by RF magnetron co-sputtering system by Ag and ZnO tragets,using annealing system activates the dopant atoms in the films.The results showed that the undoped ZnO exhibits n-type conductive,and Ag-ZnO exhibite p-type conductive.By XRD diffraction spectra, the peak position of the Ag-ZnO films are lower than normal ZnO (002) peak position of 34.36°.This is caused by Ag ions replaves the Zn ions,because which Ag radius greater than Zn radius.The current-voltage characteristics,Ni/ITO and ITO-ZnO as electrode deposition of p-type and n-type present ohimc contact.In this study, we fabricated p-ZnO/n-ZnO homostructures diode on silicon substrate，In current-voltage characteristics,when the voltage is positive or negative 2.5 V,the current ratio is about 0.96,which shows no rectifying characteristcs,deposited Ni/ION above surface p-n diode,showing the schottky contact,that the p-type ZnO transforms into n-type conductive. XPS diagrams show that when Ag-ZnO and n-ZnO contact, Ag-ZnO film found that Ag atoms are in the metallic state in thin film. In the middle of the Ag-ZnO and n-ZnO added a layer of i-ZnO From the Raman spectra,found that p-i-n ZnO homostructures at 412 cm-1 peak significantly. The p-type ZnO deposited at the top of the i-ZnO/n-ZnO, and the silver atoms replaced the zinc atoms. in the p-type ZnO film In current-voltage characteristics,Ag-ZnO/i-ZnO/n-ZnO homojunction diodes exbihit poor rectifying characteristics,and the diodes turn-on voltage of about 1.69 V.In order to optimize the homojunction diode,change the i-ZnO into a double hetero-junction(AlN-ZnO/ZnO/AlN-ZnO;DH) structure with different active layer of thinckness. XPS diagrams show that Ag-ZnO deposited on the DH/n-ZnO surface, p-type ZnO have that Ag atom is silver and oxygen bond balance in a thin film, maintenance of p-type ZnO. Reducing the thickness of the active layer from the current-voltage measurements found to reduce the series resistance and turn-on voltage.When the double DH is add,the current ratio is higher than p-i-n homojunction diodes.The thermionic emission theory and Cheung’s formula to explore the ideal factor and Schottky barrier.

Gli stili APA, Harvard, Vancouver, ISO e altri

40

HUANG, YAO-TE, e 黃耀德. "Raman scattering enhancement by 3D ZnO/Ag nanostructures using ferroelectric templates". Thesis, 2019. http://ndltd.ncl.edu.tw/handle/dhu8ya.

Testo completo

Abstract (sommario):

碩士
國立臺北科技大學
光電工程系
107
In this paper, a novel surface enhanced Raman scattering (SERS) substrate prepared by using a lithium niobate ferroelectric template is proposed. The ferroelectric template is fabricated using a periodic proton exchange process. The study is divided into two experiments. The first experiment was to fabricate a three-dimensional structure SERS substrate, and the second experiment was to transfer the silver particles on the SERS substrate using tape. First, the first experiment was to control the zinc oxide growth time and photoreduction silver particle time to obtain the best zinc oxide and silver nanostructures to effectively enhance the Raman signal. The X-ray diffractometer, optical microscope, scanning electron microscope and other instruments were used to measure the structural characteristics of zinc oxide nanostructure and the distribution of silver nanostructures. The paper also discussed the process parameters for the particle shape of silver nanostructures. The influence of particle size, particle size and particle size and the effect of zinc oxide. Try to combine metal nanoparticles with zinc oxide (ZnO) to investigate the effect of this three-dimensional structure on surface enhanced Raman scattering (SERS). ZnO is a hexagonal wurtzite structure. The crystal structure has the characteristics of symmetry and piezoelectric effect, and can be applied to gas detectors, surface acoustic wave elements, and the like. In order to produce a SERS substrate, this experiment uses a hydrothermal method to grow zinc oxide having a large area and uniform distribution on a lithium niobate substrate in a low temperature environment. In order to induce local surface plasma effects, we photoreducted the metal on the zinc oxide nanostructure. The local surface plasma resonance effect of the metal nanoparticles forms a "hot spot" between the metal nanoparticles, which is the region where the Raman signal is amplified. The mechanism of the amplified signal can be used to detect the surface molecule concentration. We tried zinc oxide at different growth times: 0, 10, 20, 30, 50 min to investigate the effect of zinc oxide on the surface-enhanced Raman effect of metallic nanostructures. In order to evaluate the sensitivity of the SERS substrate, that is, to detect the concentration limit, the R6G (Rhodamine 6G) dye molecules of different concentrations were prepared and the corresponding Raman intensity was measured. The experimental results show that the Raman signal can be enhanced by 12.1 times compared with the SERS substrate without ZnO nanostructure, and the Raman intensity uniformity of twelve points on the SERS substrate is 8.4%. The measured limit concentration is 10-8 M R6G molecules, and the enhancement factor is calculated up to 2.78109. It is also confirmed that the combination of zinc oxide and metal nanoparticles can make the SERS substrate have better characteristics. The second part is tape transfer, using three different tapes: transparent tape, invisible tape, insulating tape, SERS substrate tape transfer process for periodic nature exchange annealing and hydrofluoric acid etching, allowing silver particles to Transfer a large area to the tape, use OM to observe the transfer condition of the tape and retain the residual glue, and use the absorption spectrum to judge the transfer effect of the silver particles.

Gli stili APA, Harvard, Vancouver, ISO e altri

41

CHEN, SYUAN-YE, e 陳炫曄. "Temperature and Atmosphere Dependence of Ag-doped P-type ZnO Thin Film". Thesis, 2018. http://ndltd.ncl.edu.tw/handle/tu78v8.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

42

CHAO, SYUN-RU, e 趙珣如. "Preparation of Ag-doped ZnO/CuO Heterojunction Gas Sensor with Room Temperature". Thesis, 2019. http://ndltd.ncl.edu.tw/handle/k8yt4b.

Testo completo

Abstract (sommario):

碩士
國立高雄科技大學
化學工程與材料工程系
107
In this study, inkjet printing technology was used to prepare a looped electrode composed of silver nanoparticles on flexible polyimide (PI) films. Pure ZnO and CuO were synthesized by hydrothermal method. ZnO, CuO and Ag doped ZnO/CuO were used as sensing layer and coated onto sliver electrode. To improve the traditional semiconductor gas sensor needs to be applied the high temperature environment, the gas sensing was tested under room temperature with UV LED. Silver particles was synthesized by a simple polyol reduction method. The silver nanoparticle was formulated into 5 wt% silver ink, and the ink was filled in a commercially available EPSON T50 printer ink cartridge. The silver loop type electrode is printed on the polyimide film and then coated with a layer of gas sensitive material, wherein the sensing layer is ZnO (N-type), CuO (P-type), the formation of heterogeneous interface (P-N Junction) of ZnO mixed with CuO (ZnO/CuO), and silver doped ZnO/CuO to complete the preparation of sensors. The sensors are placed in a homemade gas sensing chamber, and the sensing test is carried out under reducing gas atmosphere (0-400 ppm) at room temperature with a low wattage UV-LED (10 W) lamp irradiated. The sensors was connected to a source meter (Keithley 2400), and the current value was read at different reducing gas concentrations. After the computer software was recorded, the sensing performance of the gas sensor at room temperature was investigated. The gas sensing results revealed that the Ag doped Zno/CuO based gas sensor has superior gas sensing properties like, high response(95.9), good stability, and fast response (3 s) and recovery (5 s) time towards 50 ppm acetone gas at room temperature compared to pure ZnO(37.7/4 s/6 s), CuO(28.3/34 s/12 s)and ZnO/CuO(63.2/5 s/7 s) based sensors. The sensed instantaneous current value significantly changed with increasing acetone gas concentration, and was an effective acetone gas sensor. The sensors with UV-LED can effectively improve the limitations of conventional metal oxide semiconductor gas sensors operating at high operating temperature, and Ag doped ZnO/CuO gas sensor have good sensing ability for the acetone gas with low ppm concentration at room temperature.

Gli stili APA, Harvard, Vancouver, ISO e altri

43

Hung, Sung-Wei, e 洪松慰. "Syntheses and Characterization of Multi-functional N-doped Nano-ZnO Visible Light Photocatalyst and ZnO-Ag Nano-composite Particles". Thesis, 2007. http://ndltd.ncl.edu.tw/handle/nwa54g.

Testo completo

Abstract (sommario):

碩士
國立臺北科技大學
材料科學與工程研究所
95
In this study, N-doped ZnO nanoparticles with rod-like and tetrapod-like morphologies were synthesized on a mass scale using the DC thermal plasma approach. The N-doped ZnO nanoparticle has a strong absorption below 420 nm and significant absorption in the visible range from 450 to 650 nm. Ag nano-colloids were prepared by chemical reduction with the presence of citrate ion, which modified the surface properties of Ag nanoparticle. After complete mixing, the Ag nanoparticles can adhere to the surface of N-doped ZnO nanoparticle to form ZnO-Ag nano-composite particles (NCPs) due to the attraction between the positively charged ZnO surface and the negatively charged Ag surface. The experimental results indicate that ZnO-Ag composite has semicoherent interface boundary. The amount of Ag nanoparticles absorbed on the surface of N-doped ZnO nanoparticle, is related to the surface charge density of the N-doped ZnO nanoparticle. Citrate ions play the role of selective absorption site on N-doped ZnO nanoparticle surface. Although decomposition efficiency of methylene blue (MB) under UV irradiation does not appear to differ from each other, ZnO with a higher N-doped concentration has better decomposition performance under visible light illumination. This is due to that oxygen vacancies prolong the recombination of electron and hole. The decomposition performance of methylene blue (MB) by ZnO-Ag NCPs significantly exceeded that by N-doped ZnO nanoparticles under UV irradiation, because the Ag nanoparticles act as electron traps, which enhances electron-hole separation. However, there is almost no difference in methylene blue (MB) decomposition efficiency between the ZnO-Ag NCPs and the N-doped ZnO nanoparticles under visible light. The Ag nanoparticles behave incompletely equivalent under UV irradiation and visible light due to the surface plasmon resonance absorption of Ag nanoparticles, which is only induced by visible light. Ag nanoparticles can decompose methylene blue (MB) during illumination with visible light. Increasing the N-dopant concentration of ZnO nanoparticles improves anti-bacterial performance because oxygen vacancies prolong the recombination of electron and hole. The anti-bacterial performance of N-doped ZnO nanoparticles under visible light is better than that of commercial ZnO nanoparticles. The N-doped ZnO nanoparticles exhibit additionally the intrinsic photocatalytic activity for anti-bacterial performance. N-doped ZnO nanoparticles modified with a coating of Ag nano-dots on their surface perform as well as N-doped ZnO nanoparticles do, during 3 hours of illumination with visible light with a wavelength of 543 nm. However, the performance of ZnO-Ag NCPs is improved by approximately two orders of magnitude in the dark. Mildew resistance tests indicate N-doped ZnO nanoparticles has excellent performance of zero-level.

Gli stili APA, Harvard, Vancouver, ISO e altri

44

Zhen-YuLiu e 劉朕宇. "Performance Improvement of Inverted Polymer Solar Cells with Silver Nanoparticles Doped in Active Layer and ZnO/Ag/ZnO Multilayer Structure". Thesis, 2016. http://ndltd.ncl.edu.tw/handle/432667.

Testo completo

Abstract (sommario):

碩士
國立成功大學
微電子工程研究所
104
In this work, the ZnO/Ag/ZnO multilayer film was applied to inverted polymer solar cells (IPSCs) as electron transportation layer to improve power conversion efficiency (PCE) of IPSCs. By inserting a nano-sized Ag layer between bottom ZnO and top ZnO layer, the light transmission of electron transportation layer could be enhanced resulting from local-ized surface plasmon (LSP) of silver nanoparticles at visible wavelength. The power con-version efficiency of IPSCs with ZnO/Ag/ZnO (Ag=8 nm) electron transportation layer improved from 7.25% to 8.13%. Besides, silver nanoparticles was doped into the active layer (PTB7：PCBM) of IPSCs. The light absorption of devices could be enhanced result-ing from optical re-flection by scattering of silver nanoparticles. Compared to the active layer without silver nanoparticles, the power conversion efficiency of IPSCs with PTB7：PCBM：Ag NPs (10：15：0.4) active layer improved from 7.25% to 7.55%. Combinating ZnO/Ag/ZnO electron transportation layer and active layer with silver nanoparticles, the best performance of the IPSCs was obtained that power conversion efficiency was 8.30%.

Gli stili APA, Harvard, Vancouver, ISO e altri

45

Wang, Wen-Long, e 王文龍. "An Investigation on Microstructure and Opto-electrical Characteristics of ZnO-In/Ag-ZnO Thin Films Using the Electrical Current Mechanism". Thesis, 2009. http://ndltd.ncl.edu.tw/handle/28995019190801274461.

Testo completo

Abstract (sommario):

碩士
國立成功大學
奈米科技暨微系統工程研究所
97
Transparent conductive oxide (TCO) film needs annealing in 400~700 ℃ for 1~2 hours to obtain homogeneous crystalline texture and excellent photoelectric properties presently. Considering the application of TCO films in flexible polymer substrate, conventional high temperature annealing process is trapped. Therefore, in this thesis, the nano metallic film is used for a conductive layer, and the low-temperature electrical current characters of ZnO/In/ZnO as well as the ZnO/Ag/ZnO nano TCO structures are researched by electrical current testing. The experimental results show that the middle indium layer is a continuous film, and the interface of ZnO as well as indium has micro diffusion phenomena in the as-sputtered ZnO/In/ZnO structure; as for the as-sputtered ZnO/Ag/ZnO structure, the middle silver layer is a granular film, and part of silver sites are twins structure. The induced temperature by electrical current testing in the both ZnO sandwich structures can reach 140℃~170℃ and the crystallization as well as the electric property can be improved. In the electrical current process, the conductive layer atoms will diffuse to lower concentration sites by Joule heating and electromigration effects which increase the thickness of interfacial diffusion layer, and the ZnO sites possess doping and partial recrystallization phenomena. Therefore, the low-temperature electrical current crystallization effect can promote the electric property of ZnO film effectively. Besides, the Raman spectrum of the electrical current sample can be enhanced but most of photon energy is absorbed to promote recrystallization behavior and this behavior also lets photon intensity decrease and shift. Moreover, nano metallic layer will suppress the FTIR spectra of ZnO easily, so it is difficult to differentiate the film texture differences about the as-sputtered and the electrical current testing samples by FTIR spectra. In a word, the electrical current mechanism for TCO can induce film texture phase transformations and improve the photoelectric characteristics to provide the application of low-temperature film process.

Gli stili APA, Harvard, Vancouver, ISO e altri

46

Wu, Hsiao-min, e 吳曉旻. "Hydrogen production by partial oxidation of methanol over Au-Ag/ZnO-Fe2O3 catalyst". Thesis, 2008. http://ndltd.ncl.edu.tw/handle/52815843662997765340.

Testo completo

Abstract (sommario):

碩士
國立中央大學
化學工程與材料工程研究所
96
Au-Ag/ZnO-Fe2O3 bimetallic catalysts prepared by co-precipitation method were studied to produce hydrogen from partial oxidation of methanol reaction (CH3OH+0.5O2→2H2+CO2, POM) for fuel cell application. TGA analysis was used to investigate the thermal decomposition of catalyst precursors. During calcination, the main weight loss of catalyst precursor was about 540 K. It was due to the hydrozincite (Zn5(CO3)2(OH)6) decomposed to ZnO. XRD results revealed that no diffraction peak of Au and Ag could be seen before and after calcination; only hydrozincite could be found in the patterns which transformed into the well crystalline ZnO structure. The TPR results showed that the transition-metal of catalyst weakened the Fe-O bond leading to the better reducibility of iron. TEM results revealed that calcination process did not have obvious influence on metal particle size. Thus, the effect of particle size to catalytic activity could be ignored. O2/CH3OH molar ratio of 0.3 exhibited better activity than the ratio of 0.5, theoretical value of POM reaction. Less MD (CH3OH→2H2+CO) reaction occurred resulted in lower CO selectivity. At lower reaction temperature, even it showed lower CO selectivity, the MC reaction predominated which lead to the decrease of H2 selectivity. When the reaction temperature increase to 523 K, POM reaction occurred with WGS (H2O+CO→CO2+H2) reaction, and had the lowest CO selectivity.

Gli stili APA, Harvard, Vancouver, ISO e altri

47

Sung, Wen-Ting, e 宋文婷. "Transformation and Fate of Nanoscale ZnO, Ag, and CeO2 in Different Aquatic Environments". Thesis, 2012. http://ndltd.ncl.edu.tw/handle/26674758824683525897.

Testo completo

Abstract (sommario):

碩士
國立中山大學
環境工程研究所
100
The fate and transformation of laboratory-prepared nano-ZnO, nano-Ag and nano-CeO2 in three aqueous solutions under different environmental conditions were investigated in this work. Over the past decades nanomaterials have been widely used in different technical fields and consumer goods. As a result, nanomaterials might enter the environmental media via different routes and then posed potential hazards to the environment and human health. Researches in this regard have received much attention worldwide. In this work it was found that the solubility of each nanomaterial was highly influenced by the solution pH, but not by the solution temperature. The maximal solubility for the tested nanomaterials was obtained at pH 3, namely about 100% for nano-ZnO and lower than 2% for both nano-Ag and nano-CeO2. The solution pH and ionic strength were found to affect the stability of nanoparticles in different aquatic environments. For the solution pH of higher than the isoelectric point of the concerned nanomaterial, the higher the solution pH is, the greater the degree of stabilization of nanoparticles would be. On the contrary, nanoparticles aggregated as the ionic strength of the solution exceeded its critical aggregation concentration (CAC). CAC for each concerned nanomaterial could also be graphically determined as the attachment efficiency (α) of nanoparticles increased with increasing ionic strength of the solution and then leveled off after reaching CAC. Experimental results also showed that Zn(OH)2(s) would form when nano-ZnO was in the solution of pH 10. The crystalline structure of the said precipitates was confirmed by X-ray diffraction. Likewise, Ce4+ dissolved from nano-CeO2 reacted with SO42- in aqueous solution yielding Ce(SO4)2(s). Clearly, transformation of nanomaterials might take place when they are in contact with various species in different aquatic environments. Humic acid in aqueous solution was found to be beneficial to the stability of nanomaterial of concern. Efforts have also been made to study the reaction behaviors among di(2-ethylhexyl)phthalate, erythromycin, and selected nanomaterials when they co-existed in the same solution. Their interactions, however, seemed to be unobvious. In this work it was found that under sunlight irradiation nano-ZnO did show its antibiotic effect due to photocatalysis. Nano-Ag was proven to have a strong antibacterial ability even in natural aquatic environments. It yielded the total bacteria survival ratio of less than 2% within one hour of reaction. In summary, the findings of this study showed that the behaviors of nano-ZnO, nano-Ag, and nano-CeO2 in aqueous solutions could be greatly influenced by different factors in different reaction systems.

Gli stili APA, Harvard, Vancouver, ISO e altri

48

Tang, Tsung-Yeh, e 湯宗曄. "Preparation and photocatalytic activity of Ag2O nps and Ag2O/Ag-ZnO nano-composites". Thesis, 2013. http://ndltd.ncl.edu.tw/handle/48145774380481253382.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

49

Chu, Chang-Pei, e 朱昌珮. "Application of ZnO Nanowires Modified with CuxO and Ag in NOx Gas Sensing". Thesis, 2018. http://ndltd.ncl.edu.tw/handle/9c7sq8.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

50

Sahoo, S. K. "Synthesis and characterization of Ag doped ZnO-PVP composite nanofibers by electrospinning method". Thesis, 2014. http://ethesis.nitrkl.ac.in/5855/1/E-58.pdf.

Testo completo

Abstract (sommario):

One-dimensional (1D) nanomaterials such as nanowires, nanotubes, nanorods, nanofibers and nanobelts have drawn a lot of attention arising out oftheir unique optical, magnetic, electrical, and otheremerging properties. Among them nanofibers provide several amazing characteristics such as very large surface area to volume ratio, high porosity, high gas permeability, small interfibrous pore size, flexibility in surface functionalities. A number of methods have been used to fabricate nanofibers but electrospinning only method to be the simplest, costeffective and highly versatile technique that has been widely used for the fabrication continuous fibers. In the present work we have synthesized ZnO-PVP composite nanofiber and Ag doped ZnO-PVP composite nanofibers by electrospinning method. The formation, crystalline phase and morphology of the prepared nanofibers were analyzed by FT-IR spectroscopy, XRD and FE-SEM analytical techniques. Formation of ultra-fine continuous smooth fibers with diameter in the range of 150-450 nm and length up to several microns was observed in case of ZnO-PVP composite nanofiber. However, in case of Ag doped ZnO-PVP composite nanofibers, no significant change in fibers diameter was observed. The magnified SEM images indicate the formation of around 20-50 nm spherical Ag particles on the surface of the nanofiber. The formation of ZnO in composite nanofiber was confirmed by XRD analysis. Furthermore, additional peaks of Ag3O4 phase was observed in the XRD pattern of Ag doped ZnO-PVP composite nanofiber.

Gli stili APA, Harvard, Vancouver, ISO e altri

Tesi sul tema "ZnO/Ag"

Cita una fonte nei formati APA, MLA, Chicago, Harvard e in molti altri stili