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Статті в журналах з теми "ZnO photocatalysis"
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Teye, Godfred Kwesi, Jingyu Huang, Yi Li, Ke Li, Lei Chen, and Williams Kweku Darkwah. "Photocatalytic Degradation of Sulfamethoxazole, Nitenpyram and Tetracycline by Composites of Core Shell g-C3N4@ZnO, and ZnO Defects in Aqueous Phase." Nanomaterials 11, no. 10 (October 4, 2021): 2609. http://dx.doi.org/10.3390/nano11102609.
Повний текст джерелаАнотація:
The synthesis of photocatalysts with high charge separation and transfer efficiency are of immense significance in the process of using photocatalysis technology for wastewater treatment. In this study core shell g-C3N4@ZnO, and ZnO defects photocatalysts presented an improved morphology in its characterization using techniques such as SEM, DRS, PL, MS, EIS, and XRD, and enhanced photodegradation of sulfamethoxazole, Nitenpyram and Tetracycline. Different composites were obtained as confirmed by the various characterization techniques studied, including core shell g-C3N4@ZnO, and ZnO defects photocatalyst. The synthesized photocatalysts showed high visible light absorption efficiency within a range of ~655 to 420 nm. Core shell g-C3N4@ZnO, and ZnO defects photocatalysts demonstrated high photocatalytic activity ascribed to high load separation and transition as shown in PL, Photocurrent reaction and EIS. It is understandable that core shell g-C3N4@ZnO, and ZnO defects photocatalysts have been confirmed to be one of the ultimate promising entrants for photocatalyst scheming.
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Pujiarti, Yuly, Suyanta Suyanta, and Eko Sri Kunarti. "A Visible Light-Induced Fe3O4/ZnO-Cu Nanocomposite and its Photocatalytic Activities for Rhodamine B Photodegradation." Key Engineering Materials 884 (May 2021): 60–66. http://dx.doi.org/10.4028/www.scientific.net/kem.884.60.
Повний текст джерелаАнотація:
Synthesis of Fe3O4/ZnO-Cu nanocomposite photocatalyst has been conducted. The synthesis was carried out using the co-precipitation method with the variation of Cu concentration and modification by Fe3O4 magnetic material. As synthesized photocatalysts were characterized using FTIR, XRD, TEM, and SR UV-Visible. Photocatalytic activities of samples were evaluated through Rhodamine B degradation under visible light irradiation. The results showed that a sample with Fe3O4/ZnO-Cu 1% has smaller band gap energy of 2.90 eV and the highest photocatalytic activity than pure ZnO or Fe3O4-modified ZnO (Fe3O4/ZnO-Cu 0%) under visible light. The percentage of Rhodamine B degradation was approximately 89.41% during 120 min of visible light illumination. Moreover, the photocatalyst materials could be easily separated after photocatalysis which is due to the magnetic property of Fe3O4 material. Therefore, Cu-doped ZnO with Fe3O4 modification has been an efficient and effective visible-light-induced photocatalyst in removing non-biodegradable Rhodamine B dyes.
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Sánchez, Luis A., Brian E. Huayta, Pierre G. Ramos, and Juan M. Rodriguez. "Enhanced Photocatalytic Activity of ZnO Nanorods/(Graphene Oxide, Reduced Graphene Oxide) for Degradation of Methyl Orange Dye." Journal of Physics: Conference Series 2172, no. 1 (February 1, 2022): 012013. http://dx.doi.org/10.1088/1742-6596/2172/1/012013.
Повний текст джерелаАнотація:
Abstract ZnO has been well-known as a significant photocatalyst material due to its high surface area, efficient charge transport, and superior photosensitivity. Even though photocatalysis using bare ZnO NRs is useful in pollutant remediation, two main drawbacks scale down their performance as photocatalysts. First, ZnO NRs absorb mainly the UV light, which compromises a small portion of the solar spectrum, and second, the high recombination rate in the ZnO NRs prevents the path of electron-hole outward and then reduces the photocatalysis efficiency. In this work, ZnO-NRs, ZnO-NRs/Graphene Oxide (GO), and ZnO-NRs/Reduced Graphene Oxide (rGO) array composites were vertically grown on conductive glass substrates of SnO2:F (FTO). The films were synthesized by hydrothermal method using ZnO seed layers deposited by spray pyrolysis technique. The nanosheets of GO and rGO were anchored onto the surface of the as-prepared ZnO-NRs by using the spray deposition technique (SDT). The photocatalytic activity of these materials was studied by analyzing the degradation of methylene orange (MO) in an aqueous solution under ultraviolet light, and we found that the decoration of ZnO-NRs with nanosheets of GO and rGO resulted in a significant enhancement of the photocatalytic degradation efficiency, where ZnO-NRs/rGO are more efficient than ZnO-NRs/GO and the latter better than pure ZnO-NRs.
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Loka, Chadrasekhar, and Kee-Sun Lee. "Enhanced Visible-Light-Driven Photocatalysis of Ag/Ag2O/ZnO Nanocomposite Heterostructures." Nanomaterials 12, no. 15 (July 23, 2022): 2528. http://dx.doi.org/10.3390/nano12152528.
Повний текст джерелаАнотація:
Visible-light-driven photocatalysis is one promising and efficient approach for decontaminating pollutants. Herein, we report the combination of localized surface plasmon resonance (LSPR) and p-n heterojunction structure Ag-Ag2O-ZnO nanocomposite synthesized by a hydrothermal process for the suppression of photogenerated electron-hole pair recombination rates, the extension of the absorption edge to the visible region, and the enhancement of photocatalytic efficiency. The prepared nanocomposites were investigated by standard analytical techniques and the results revealed that the synthesized powders were comprised of Ag, Ag2O, and ZnO phases. Photocatalytic activity of the photocatalyst tested for methylene blue, methyl orange, and rhodamine B showed the highest photocatalytic degradation efficiency: 97.3%, 91.1%, and 94.8% within 60 min under visible-light irradiation. The average lifetime of the photogenerated charge carriers was increased twofold in the Ag-Ag2O-ZnO photocatalyst (~10 ns) compared to the pure ZnO (~5.2 ns). The enhanced photocatalytic activity resulted from a decrease of the charge carrier recombination rate as inferred from the steady-state and time-resolved photoluminescence investigations, and the increased photoabsorption ability. The Ag-Ag2O-ZnO photocatalyst was stable over five repeated cyclic photodegradation tests without showing any significant changes in performance. Additionally, the structure indicated a potential for application in environmental remediation. The present study showcases the robust design of highly efficient and reusable visible-light-active photocatalysts via the combination of p-n heterojunction and LSPR phenomena.
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Kočí, Kamila, Martin Reli, Ivana Troppová, Marcel Šihor, Tereza Bajcarová, Michal Ritz, Jiří Pavlovský, and Petr Praus. "Photocatalytic Decomposition of N2O by Using Nanostructured Graphitic Carbon Nitride/Zinc Oxide Photocatalysts Immobilized on Foam." Catalysts 9, no. 9 (August 30, 2019): 735. http://dx.doi.org/10.3390/catal9090735.
Повний текст джерелаАнотація:
The aim of this work was to deposit cost-effective g-C3N4/ZnO nanocomposite photocatalysts (weight ratios of g-C3N4:ZnO from 0.05:1 to 3:1) as well as pure ZnO and g-C3N4 on Al2O3 foam and to study their photocatalytic efficiency for the photocatalytic decomposition of N2O, which was studied in a home-made batch photoreactor under ultraviolet A irradiation (λ = 365 nm). Based on the photocatalysis measurements, it was found that photocatalytic decomposition of N2O in the presence of all the prepared samples was significantly higher in comparison with photolysis. The photoactivity of the investigated nanocomposite photocatalysts increased in the following order: g-C3N4/ZnO (3:1) ≈ g-C3N4/ZnO (0.45:1) ≤ g-C3N4/ZnO (2:1) ZnO < g-C3N4 < g-C3N4/ZnO (0.05:1). The g-C3N4/ZnO (0.05:1) nanocomposite showed the best photocatalytic behavior and the most effective separation of photoinduced electron–hole pairs from all nanocomposites. The key roles played in photocatalytic activity were the electron–hole separation and the position and potential of the valence and conduction band. On the other hand, the specific surface area and band gap energy were not the significant factors in N2O photocatalytic decomposition. Immobilization of the photocatalyst on the foam permits facile manipulation after photocatalytic reaction and their repeated application.
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Le Pivert, Marie, Nathan Martin, and Yamin Leprince-Wang. "Hydrothermally Grown ZnO Nanostructures for Water Purification via Photocatalysis." Crystals 12, no. 3 (February 22, 2022): 308. http://dx.doi.org/10.3390/cryst12030308.
Повний текст джерелаАнотація:
Semiconductor-based photocatalysis is a well-known and efficient process for achieving water depollution with very limited rejects in the environment. Zinc oxide (ZnO), as a wide-bandgap metallic oxide, is an excellent photocatalyst, able to mineralize a large scale of organic pollutants in water, under UV irradiation, that can be enlarged to visible range by doping nontoxic elements such as Ag and Fe. With high surface/volume ratio, the ZnO nanostructures have been shown to be prominent photocatalyst candidates with enhanced photocatalytic efficiency, owing to their being low-cost, non-toxic, and able to be produced with easy and controllable synthesis. Thus, ZnO nanostructures-based photocatalysis can be considered as an eco-friendly and sustainable process. This paper presents the photocatalytic activity of ZnO nanostructures (NSs) grown on different substrates. The photocatalysis has been carried out both under classic mode and microfluidic mode. All tests show the notable photocatalytic efficiency of ZnO NSs with remarkable results obtained from a ZnO-NSs-integrated microfluidic reactor, which exhibited an important enhancement of photocatalytic activity by drastically reducing the photodegradation time. UV-visible spectrometry and high-performance liquid chromatography, coupled with mass spectrometry (HPLC-MS), are simultaneously used to follow real-time information, revealing both the photodegradation efficiency and the degradation mechanism of the organic dye methylene blue.
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Zhang, Yangyang, Manoj K. Ram, Elias K. Stefanakos, and D. Yogi Goswami. "Synthesis, Characterization, and Applications of ZnO Nanowires." Journal of Nanomaterials 2012 (2012): 1–22. http://dx.doi.org/10.1155/2012/624520.
Повний текст джерелаАнотація:
ZnO nanowires (or nanorods) have been widely studied due to their unique material properties and remarkable performance in electronics, optics, and photonics. Recently, photocatalytic applications of ZnO nanowires are of increased interest in environmental protection applications. This paper presents a review of the current research of ZnO nanowires (or nanorods) with special focus on photocatalysis. We have reviewed the semiconducting photocatalysts and discussed a variety of synthesis methods of ZnO nanowires and their corresponding effectiveness in photocatalysis. We have also presented the characterization of ZnO nanowires from the literature and from our own measurements. Finally, a wide range of uses of ZnO nanowires in various applications is highlighted in this paper.
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Su, Xiaowen, Xiaolei Zhao, Chao Cui, Ning Xi, Xiao Li Zhang, Hong Liu, Xiaowen Yu, and Yuanhua Sang. "Influence of Wurtzite ZnO Morphology on Piezophototronic Effect in Photocatalysis." Catalysts 12, no. 9 (August 25, 2022): 946. http://dx.doi.org/10.3390/catal12090946.
Повний текст джерелаАнотація:
A piezoelectric field promotes the photocatalytic activity of a photocatalyst by helping separating photo-generated charge carriers. Wurtzite phase ZnO is a typical photocatalyst with a piezoelectric property, thus self-assisted photocatalysis with ZnO based on the piezophototronic effect can be achieved. ZnO nanorods or nanowires with a clear c-axis have been well studied, while other morphologies have not been fully discussed. In this work, we prepared wurtzite phase ZnO with four different morphologies. By comparing their photocatalytic activity for degradation of Rhodamine B under the same mechanical energy source provided by ultrasound, the effect of morphology and exposed facets on photo-induced charge separation were highlighted. The ZnO nanowire photocatalyst delivered an impressive improvement in photocatalytic efficiency when ultrasound driven, suggesting that the morphology-related piezophototronic effect had a positive effect on separation of photo-generated charge carriers, and more exposed active facets benefitted the utilization of charge carriers.
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Sayury Miyashiro, Carolina, and Safia Hamoudi. "Palladium and Graphene Oxide Doped ZnO for Aqueous Acetamiprid Degradation under Visible Light." Catalysts 12, no. 7 (June 28, 2022): 709. http://dx.doi.org/10.3390/catal12070709.
Повний текст джерелаАнотація:
Acetamiprid is a neonicotinoid insecticide widely used in pest control. In recent years, it has been considered as a contaminant in groundwater, lakes, and rivers. Photocatalysis under visible light radiation proved to be an effective process for getting rid of several organic pollutants. In the present work, photodegradation of aqueous acetamiprid was investigated over bare zinc oxide (ZnO) photocatalyst as well as ZnO doped with either palladium or palladium combined with graphene oxide. Both ZnO and doped-ZnO were synthesized via a microwave-assisted hydrothermal procedure. The obtained photocatalysts were characterized using different techniques. After 5 h of reaction at ambient temperature under visible light irradiation, acetamiprid conversions attained ca. 38, 82, and 98% in the presence of bare ZnO, Pd-doped ZnO and Pd-GO-doped ZnO photocatalysts, respectively, thus demonstrating the positive effect of Pd- and GO-doping on the photocatalytic activity of ZnO. In addition, Pd-GO-doped ZnO was shown to keep its activity even when it is recycled five times, thus proving its stability in the reaction medium.
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El-Sayed, Fatma, Mai S. A. Hussien, Thekrayat H. AlAbdulaal, Ahmed Ismail, Heba Y. Zahran, Ibrahim S. Yahia, Mohamed Sh Abdel-wahab, Yasmin Khairy, Tarik E. Ali, and Medhat A. Ibrahim. "Comparative Degradation Studies of Carmine Dye by Photocatalysis and Photoelectrochemical Oxidation Processes in the Presence of Graphene/N-Doped ZnO Nanostructures." Crystals 12, no. 4 (April 11, 2022): 535. http://dx.doi.org/10.3390/cryst12040535.
Повний текст джерелаАнотація:
The goal of this study was to synthesize a UV-light-active ZnO photocatalyst by modifying it with nitrogen and graphene, then applying it to the degradation of carmine dye utilizing two promising technologies: photocatalysis and electrochemical oxidation (E.O.). Different techniques were used to analyze the prepared photocatalysts, such as Fourier transform infrared (FTIR), scanning electron microscopy (SEM), and X-ray diffraction (XRD). According to XRD measurements, the produced nanocomposite possesses a hexagonal wurtzite structure, indicating ZnO and markedly crystalline. For photocatalytic applications, the results revealed that the 0.001 g of G/N-doped ZnO catalyst achieved 66.76% degradation of carmine and kinetic degradation rates of 0.007 min−1 within 185 min by photocatalysis under UV light irradiation. In comparison, the same sample reached 100% degradation of carmine and kinetic degradation rates of 0.202 min−1 within 15 min using the electrochemical oxidation method. The improved photocatalytic activity of as-produced nanocomposites can be attributed to intermediate levels in the prohibited bandgap energy and the enhanced oxygen vacancies caused by nitrogen doping. The electrolyte (NaCl) on the degradation of the carmine dye was tested, and the findings indicated that the dye molecules were photodegraded by the 0.001 g of G/N-doped ZnO nanocomposite after a 15 min time interval. The data presented in this work for the carmine breakdown in water give intriguing contrasts between photocatalytic, indirect electrochemical oxidation, and photoelectrochemical oxidation. The action of chlorinated oxidative species, predominantly HClO, which were electrogenerated at the electrode surface due to the chloride ion’s oxidation in solution, induced indirect electrochemical oxidation degradation. This study also revealed that the modifications made to ZnO were beneficial by improving its photocatalytic activities under UV light, as well as a comparison of photocatalysis and electrochemical oxidation processes to determine which technique is best for treating carmine in effluents with high chloride ions.
Дисертації з теми "ZnO photocatalysis"
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Ramirez, Canon Anyela M. "Nanostructured ZnO films for water treatment by photocatalysis." Thesis, University of Bath, 2015. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.687342.
Повний текст джерелаАнотація:
The development of nanostructured materials for environmental applications has received considerable attention in recent years. The properties of nanoparticles or nanostructured materials, such as large surface areas or high aspect ratios, translate into large improvements in the performance of existing devices and in the discovery of novel applications. On the other hand, photocatalysis is an attractive technology for the elimination of organic pollutants in water due to its simplicity, ease of implementation and reasonable cost compared to other advanced oxidation processes. A key disadvantage of many photocatalysts is their use in powder form which makes their recovery from treated water costly. In addition, incomplete removal can lead to accumulation over time with adverse effects to the environment. As a result significant effort has been placed in immobilizing photocatalytic materials on different substrates. The immobilization of photocatalyst results in a decrease in photocatalytic performance mainly due to reduction of surface area; therefore, research is now focusing on developing nanostructured materials which combine the attributes of nanotechnology and photocatalysis. In the present thesis, a systematic study of the relationship between properties of supported ZnO nanostructures and their photocatalytic activity was performed. Analysis was carried out by producing ZnO nanostructured films via anodization. The effects of voltage, temperature, reaction time and type of electrolyte on the morphology of ZnO nanostructures was studied. Results show that the type of electrolyte and its concentration determine the morphology and size of the nanostructures. Voltage, time and temperature affect the distribution and density of the nanostructures along the surface and affect the crystal size of the ZnO. The band gaps of the films were in the range of 3.27 and 3.50 eV. Although ZnO is a hydrophilic material, some of the films displayed hydrophobic and super-hydrophobic behaviour. The results obtained in this study and some data already published in the literature were correlated to the synthesis parameters, and were used to devise design guidelines to obtain ZnO films with specific nanostructures and macroscopic properties by controlling the anodization parameters. The photocatalytic activity of the ZnO nanostructured films (ZnO-NFs) were studied using three different photocatalytic reactors, (i) a thermo-stated batch reactor, (ii) a recirculating flat plate reactor, and (iii) a recirculating tubular annular reactor. Phenol and methyl orange (MO) were used as a model compounds. It was found that crystal size does not affect the photocatalytic performance of the films while morphology has an important impact on the degradation of phenol. The stability of the ZnO nanostructures was tested under different levels of oxygen, degradation of phenol occurred even at anoxic conditions following the Mars-van Krevelen mechanism. The formation of new nanostructures produced during the photocatalytic reaction was studied and a mechanism of formation was proposed. The study of the photocatalytic performance in the flat plate reactor showed that there was a mass transfer limitation in the process. ZnO nanostructures showed higher photocatalytic activity and morphology stability in the tubular annular reactor. Degradation of MO and phenol was produced in darkness by the nanostructures supported in Zn foil. It was also demonstrated that oxygen plasma post-treatment enhances the photocatalytic activity of the ZnO-NF by 36% while making the photocatalyst more stable for the photocatalytic degradation of phenol compared to those treated with heat. An electrical current was applied to the photocatalyst in the tubular annular reactor, which improved the degradation of phenol and participated in the formation of nanostructures in the Zn wire surface.
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PERIASAMY, VAIRAVANATHAN PONRAJESH. "BILAYER FILM CATALYSIS OF ZnO-CdO AND A COMPARISON WITH ZnO FILM CATALYSIS." Miami University / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=miami1196312783.
Повний текст джерела
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Kwiatkowski, Maciej. "ZnO(core)/TiO2(shell) composites : influence of TiO2 microstructure, N-doping and decoration with Au nanoparticles on photocatalytic and photoelectrochemical activity." Thesis, Bourgogne Franche-Comté, 2017. http://www.theses.fr/2017UBFCK046/document.
Повний текст джерелаАнотація:
Le but de la thèse est d'étudier l'influence de la microstructure des composites ZnO/TiO2 sur leurs propriétés dans la dégradation photocatalytique des polluants organiques et dans l'oxydation de l'eau photoassistée. Pour réaliser cette étude, nous avons choisi la conception basée sur des nano bâtonnets ZnO supportés sur une électrode de verre recouverte d'ITO (Indium Tin Oxide). Les nano bâtonnets de ZnO ont ensuite été recouverts d'une couche de TiO2 dans différentes conditions. La composition et la microstructure des composites ZnO(cœur)/TiO2(coquille) ont été modifiées dans le but d'élucider comment ces paramètres influencent leur activité photocatalytique. La couche TiO2 de morphologie différente (discontinue ou compacte) a été élaborée. Nous avons montré que le composite contenant la couche de TiO2 discontinue possède une activité plus élevée dans la dégradation de MB et dans l'oxydation de H2O sous 400 nm. Cette photoactivité améliorée a été attribuée à une meilleure accessibilité pour les réactifs de l'interface ZnO/TiO2 à travers la couche de TiO2. Aussi nous avons pu améliorer l'activité des composites sous la lumière visible. Dans ce but, les composites constitués de nano bâtonnets de ZnO supportés sur ITO ont été recouverts de TiO2 dopé à l'azote et décorés de nanoparticules d'or. Il a été trouvé que même une faible charge d'or (0,37% at.) permet une augmentation de 60% de la vitesse de décoloration photocatalytique du MB sous la lumière visible par rapport à l'échantillon sans or en raison de l'effet plasmonique. Un dopage simultané à l'azote et à l'or a permis également de multiplier par trois le photocourant dans l'oxydation photoassistée de l'eauThe aim of the thesis is to study the influence of microstructure of ZnO/TiO2 composites on their properties in photocatalytic degradation of organic pollutants, and in photoassisted water oxidation. To realize such study we chose the design based on ZnO nanorods supported on ITO (Indium Tin Oxide)-coated glass electrode. The ZnO nanorods were then covered with a layer of TiO2 under different conditions. The composition and microstructure of the obtained ZnO(core)/TiO2(shell) composites were modified in the aim to elucidate how these parameters influence their photocatalytic activity. The results of studies lead to elaboration of two most distinctive variants of sol-gel procedure that allow to deposit TiO2 layers of controlled thicknesses and different morphology (rugged or compact). The composite containing the rugged TiO2 layer was shown to possess significantly higher activity in MB degradation and in photoassisted H2O oxidation under 400 nm. This improved photoactivity was attributed to a higher porosity and better accessibility of ZnO/TiO2 interface region through the rugged TiO2 layer by the reagents. The effort was also made to enhance the visible light activity of the composites. To this aim the composites consisting of ITO-supported ZnO nanorods covered with nitrogen-doped titanium dioxide and decorated with Au nanoparticles. It was found that even a low Au loading (0.37% at.) resulted in 60% enhancement of photocatalytic decolorization of MB under visible light with respect to the Au-free sample owing to plasmonic effects. A simultaneous N-doping and Au decoration allowed also to multiply by three the photocurrent in photoassited water oxidation
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Donat, Florian. "Microréacteurs photocatalytiques utilisant des oxydes métalliques semi-conducteurs sensibilisés par des Quantum Dots CuInS2/ZnS." Thesis, Université de Lorraine, 2017. http://www.theses.fr/2017LORR0085/document.
Повний текст джерелаАнотація:
La pollution actuelle des effluents hospitaliers par des médicaments, nécessite le développement de nouvelles techniques de traitement, la photocatalyse étant l’une des plus efficaces pour remédier à ce type de pollution. Cependant, les oxydes métalliques utilisés pour la photocatalyse (TiO2, ZnO, …) ne sont activables que sous irradiation UV. L’association de ces oxydes à des Quantum Dots (QDs), crée une hétérojonction qui étend la zone d’activation du photocatalyseur vers les rayonnements visibles et diminue les recombinaisons des porteurs de charges. La première partie de ce travail décrit le développement d’un photocatalyseur activable sous irradiation solaire pour la dégradation du colorant Orange II. Nous avons d’abord caractérisé l’hétérojonction créée entre ZnO et les QDs CuInS2/ZnS (ZCIS) puis étudié leur efficacité photocatalytique, en regardant notamment leurs capacités à générer des espèces réactives de l’oxygène. Dans la seconde partie, nous avons évalué la photodégradation d’un agent anticancéreux, l’Ifosfamide, présent dans les effluents hospitaliers. Pour cela, des réacteurs fermés agités et des microréacteurs ont été utilisés. Dans les deux cas, l’Ifosfamide, ainsi que ses intermédiaires de dégradation, sont photodégradés efficacement par le catalyseur ZnO/ZCIS sous une irradiation solaire de faible intensité (5 mW/cm2). Dans le cas des microréacteurs, le dépôt du catalyseur dans le microcanal a été optimisé et sa stabilité évaluée. Les résultats montrent que le catalyseur ZnO/ZCIS est réutilisable cinq fois sans perte d’activité, témoignant d’une bonne recyclabilité, ce qui en fait un bon candidat pour des applications photocatalytiquesThe pollution of hospital effluents by pharmaceutical drugs, requires the development of new treatment techniques. Among these processes, photocatalysis is one of the most efficient one and allows the remediation of this kind of pollution. However, metal oxides used for photocatalysis (TiO2, ZnO, …) can only be activated by UV light. The association of these oxides with quantum dots (QDs) creates an heterojunction, which not only allows to extend the activation spectrum of the photocatalyst to the visible region but also decreases the charge carriers recombinations. The first part of this work describes the development of a catalyst responding to solar light irradiation for the degradation of the Orange II dye. First, we characterized the heterojunction created between ZnO and the CuInS2/ZnS (ZCIS) QDs and evaluated their photocatalytic efficiency. This work was undertaken by evaluating the capacity of the ZnO/ZCIS catalyst to produce reactive oxygen species (ROS). In the second part, we studied the photodegradation of the antineoplastic agent Ifosfamide commonly found in hospital effluents. For this purpose, closed and agitated reactors but also microreactors were used. In both cases, Ifosfamide, and the compounds originating from its degradation, can be fully photodegraded under simulated light of weak intensity (5 mW/cm2) using the ZnO/ZCIS catalyst. In the case of microreactors, the deposition of the catalyst was optimized and its stability evaluated. Results obtained demonstrate that the ZnO/ZCIS catalyst can be reused, at least five times, without significant loss in activity, thus demonstrating its ability to be used in real photocatalytic applications
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Herring, Natalie. "Formation Mechanisms and Photocatalytic Properties of ZnO-Based Nanomaterials." VCU Scholars Compass, 2013. http://scholarscompass.vcu.edu/etd/494.
Повний текст джерелаАнотація:
Zinc Oxide (ZnO) is one of the most extensively studied semiconductors because of its unique properties, namely, its wide band gap (3.37 eV) and high excitation binding energy (60 meV). These properties make ZnO a promising material for uses in a broad range of applications including sensors, catalysis and optoelectronic devices. The presented research covers a broad spectrum of these interesting nanomaterials, from their synthesis and characterization to their use as photocatalyts. A new synthetic approach for producing morphology controlled ZnO nanostructures was developed using microwave irradiation (MWI). The rapid decomposition of zinc acetate in the presence of a mixture of oleic acid (OAC) and oleylamine (OAM) results in the formation of hexagonal ZnO nanopyramids and ZnO rods of varying aspect ratios. The factors that influence the morphology of these ZnO nanostructures were investigated. Using ligand exchange, the ZnO nanostructures can be dispersed in aqueous medium, thus allowing their use as photocatalysts for the degradation of malachite green dye in water. Photocatalytic activity is studied as a function of morphology; and, the ZnO nanorods show enhanced photocatalytic activity for the degradation of the dye compared to hexagonal ZnO nanopyramids. After demonstrating the catalytic activity of these ZnO nanostructures, various ways to enhance photocatalytic activity were studied by modification of this MWI method. Photocatalytic activity is enhanced through band gap modulation and the reduction of electron-hole recombination. Several approaches were studied, which included the incorporation of Au nanoparticles, N-doping of ZnO, supporting ZnO nanostructures on reduced graphene oxide (RGO), and supporting N-doped ZnO on N-doped RGO. ZnO-based nanostructures were studied systematically through the entire process from synthesis and characterization to their use as photocatalysis. This allows for a thorough understanding of the parameters that impact these processes and their unique photocatalytic properties.
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Moussa, Hatem. "Influence de l’association de quantum dots ZnO avec des ions Cu²+ sur leur (photo)toxicité. Nouveaux matériaux ZnO/rGO pour la photocatalyse solaire." Thesis, Université de Lorraine, 2016. http://www.theses.fr/2016LORR0036/document.
Повний текст джерелаАнотація:
Ces dernières années, les énormes progrès réalisés en nanotechnologie ainsi qu’en science des matériaux ont conduit à la préparation de nombreuses nouvelles nanoparticules sans réellement connaître l’ensemble des propriétés associées à leurs dimensions. La première partie de notre travail vise à évaluer les risques et les problèmes associés aux nanomatériaux, en termes de toxicité, en utilisant des nanoparticules de ZnO. Nous avons tout d’abord étudié la capacité de ces nanoparticules à générer des espèces réactives d’oxygènes (EROs) sous irradiation UV en utilisant trois types des quantum dots (QDs) comme modèles, ZnO, ZnO dopé avec des ions Cu2+ et ZnO avec des ions Cu2+ adsorbés à sa surface. Les trois types des QDs ont montré une forte capacité à générer des EROs mais ceux modifiés par les ions Cu2+ en périphérie sont les plus producteurs. Ces QDs inhibent également le plus fortement la croissance de la bactérie E. coli. La toxicité n’est cependant pas dépendante des EROs photo-produits ni du zinc (+2) libéré par les QDs et montre qu’un mécanisme plus complexe doit être considéré. Dans une second partie, nous avons tenté d’améliorer l’activité photocatalytique de nanobâtonnets de ZnO en les associant à de l’oxyde de graphène réduit (rGO). Des nanocomposites ZnO/rGO ont été préparés par voie solvothermale et utilisés pour la phototodégradation du colorant Orange II comme modèle de polluant. Les résultats obtenus montrent que le photocatalyseur ZnO/rGO est très efficace sous irradiation solaire ou visible et qu’il est peu sensible à des variations de pH ou à la présence de perturbateurs dans le milieu. Finalement, le photocatalyseur est très stable et peut être réutilisé plus de dix fois sans perte notable d’activitéIn recent years, tremendous advances in nanotechnology and materials science have led to the synthesis of many new nanoparticles without really knowing all the properties associated with their dimensions. The first part of our work aims to evaluate the risks and problems associated with nanomaterials, in terms of toxicity, using ZnO nanoparticles. We first studied the ability of these nanoparticles to produce reactive oxygen species (ROS) under UV irradiation using three ZnO-based quantum dots (QDs) as models, ZnO, ZnO doped with Cu2+ ions and ZnO with chimisorbed Cu2+ ions at their periphery. The three QDs have a strong capacity of generating ROS but those modified with Cu2+ at their surface were found the be the highest producers. These dots were also found to inhibit more markedly the growth of the E. coli bacteria. The toxicity does neither depend on the amount of photo-generated ROS nor on the amount of Zn(+2) leaked by the QDs, thus indicating that a more complex mechanism should be considered. In a second part, we tried to improve the photocatalytic efficiency of ZnO nanorods by associating these nanomaterials with reduced graphene oxide (rGO). ZnO/rGO composites were prepared by a solvothermal method and applied for the photodegradation of Orange II used as model pollutant. Results obtained demonstrate that the ZnO/rGO photocatalyst is highly efficient under solar and under visible light irradiation and weakly sensitive to pH changes and to the presence of perturbators in the reaction medium. Finally, the photocatalyst is stable and can be reused up to ten times without significant loss of catalytic activity
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Kwiatkowski, Maciej. "ZnO(core)/TiO2(shell) composites: influence of TiO2 microstructure, N-doping and decoration with Au nanoparticles on photocatalytic and photoelectrochemical activity." Doctoral thesis, Bourgogne Franche-Comté, 2017. https://depotuw.ceon.pl/handle/item/2244.
Повний текст джерелаАнотація:
Efficient use of renewable energies is one of the most difficult technological challenges facing humanity. Among all renewable energy sources, the sunlight is considered as the most abundant and accessible one. To convert it into usable and controllable form, the modern technology relies on generation of electron-hole pairs in semiconductors upon light absorption. The obtained separated charge carriers possess extra energy brought by the converted sunlight which can be further utilized in various ways. Currently, the most common approach consists in its direct transformation into electricity in p-n junctions. Alternatively, the electrons and holes can be used to perform chemical reactions. The electrons can be transferred to reduce various organic compounds or inorganic species, while simultaneously the holes can play the role of oxidizer by subtracting the electrons from the other substances. Through these reactions it would be possible to accumulate the solar energy in chemical species allowing thus to alleviate the intermittence of the sunlight. Unfortunately, the existing materials do not easily cross the laboratory level to realize this approach on industrial scale. That is why the development of new semiconductor photocatalysts, which harvest and convert efficiently the visible part of solar spectrum, is of paramount importance.
For many years the most often studied photocatalytic materials have been ZnO and TiO2. However, it has been recently shown that composites based on ZnO and TiO2 possess even more promising properties than many other semiconductors in various photocatalytic applications. Despite many works reporting high photoactivity of these composites in different applications, the detailed information about the structure–properties correlation is lacking. In order to fill this gap we decided to focus our attention to study the influence of microstructure of ZnO/TiO2 composites on their properties in photocatalytic degradation of organic pollutants, and in application in half-reaction of ‘solar fuel’ generation, namely photoassisted water electro-oxidation. To realize such study the composites should satisfy the requirements of a high surface area and good electric conductivity. We chose therefore the design based on ZnO nanorods supported on ITO (Indium Tin Oxide)-coated glass electrode. The ZnO nanorods (NRs) were then covered with a layer of TiO2 under different deposition conditions. The composition and microstructure of the obtained ZnO(core)/TiO2(shell) composites were modified in the aim to elucidate how these parameters influence their photocatalytic activity. Consequently, the efforts were made to impart visible light activity to the elaborated ZnO/TiO2 composites by modifying titanium dioxide layers with nitrogen and decoration with Au nanoparticles.
The thesis consists of three parts: Bibliography, Experimental and Results and Discussion.
First part of the present PhD thesis, Bibliography, is dedicated to the analysis of literature concerning fundamental properties of semiconductor materials, solid/electrolyte interface as well as principles of photocatalysis and photoelectrochemical water oxidation. Also, the photocatalytic properties of ZnO and TiO2, and those of their composites are reviewed in this section. Furthermore, methods for improvement visible-light absorption are also described, i.e. N-doping and surface plasmonic effects due to the noble metal nanoparticles (Au NPs) deposited on semiconductors.
The second part, Experimental, covers the preparation procedures and characterization techniques used in the work. First, the details are given for electrochemical seeding of ITO support, hydrothermal growth of ZnO nanorods, sol-gel deposition of TiO2 (and N-doped TiO2), and photodeposition of Au NPs. Second, the characterization techniques used in realization of this project are described: SEM (Scanning Electron Microscopy), HAADF-STEM and HR-TEM (High Angle Annular Dark Field Scanning Electron Transmission Microscopy and High Resolution Transmission Electron Microscopy), XRD (X-ray Diffraction Analysis), XPS (X-ray Photoelectron Spectroscopy), EDS ‘or EDX’ (Energy Dispersive Spectroscopy) analyses connected with electron microscopy techniques, UV-vis Spectroscopy and DRS (Diffuse Reflectance UV-vis Spectroscopy, TGA-DSC (Thermogravimetry Differential Scanning Calorimetry Analysis), TOC (Total Organic Carbon) analysis, RT-PL (Room Temperature Photoluminescence Spectroscopy), electrochemical techniques including: LSV (Linear Sweep Voltammetry), CV (Cyclic Voltammetry), chronoamperometry, chronopotentiometry, as well as the set-ups elaborated by the author for the purpose of photocatalytic and photoelectrochemical measurements.
The main results of the PhD thesis are presented in the third part, Results and Discussion, consisting of four chapters.
In the first chapter (Chapter 4.1), the results of the studies on electrochemical seeding of ITO-electrode in Zn(CH3COO)2 solution are presented. The length and width of ZnO nanorods grown by hydrothermal method from Zn(NO3)2 aqueous solution on Zn/ZnO-seeded ITO substrate were shown to depend strongly on initial Zn2+ concentration and the synthesis duration. The arrays of well-separated ZnO ‘obelisk-like’ nanorods of width varied from 100 nm at tips to ~ 300 nm at bottom and average length of 1.9 µm were prepared under optimized conditions, and used as starting point for further fabrication of (core)ZnO/TiO2(shell) composites.
In the second chapter (Chapter 4.2), a simple and low-cost sol-gel method was developed in order to form TiO2 thin layers on ZnO nanorods by hydrolysis of titanium(IV) butoxide. The results of studies lead to elaboration of two most distinctive variants of sol-gel procedure that allow to deposit TiO2 layers of controlled thicknesses and different morphology (rugged or compact). The rugged TiO2 layers were obtained after 6 hours of one step sol-gel synthesis followed by calcination of the sample at
450 oC, ensuring formation of anatase-TiO2, whereas the uniform coating of 25 nm –
40 nm thickness was obtained via three successive 30 min-synthesis with the intermediate calcination of the sample after each deposition cycle. The composite containing the rugged TiO2 layer was shown to possess significantly higher activity in model pollutant (methylene blue, MB) degradation and in photoassisted H2O electro-oxidation under 400 nm monochromatic light irradiation. This improved photoactivity was correlated with the composite microstructure and attributed to a higher porosity and better accessibility of ZnO/TiO2 interface region through the rugged TiO2 layer by the reagents. The TiO2 (shell) layers of similar morphology were also prepared by atomic layer (ALD) and chemical vapor deposition (CVD) techniques and it was shown that the composites fabricated by us with the use of simple sol-gel procedure yield comparable (or even higher) photoactivity. Finally, it was confirmed by total organic carbon (TOC) analysis that the ZnO/TiO2 composites elaborated in this work are also active in decomposition of the pollutants in a dumb hill leachate solution (waste water) under 400 nm monochromatic irradiation.
In Chapter 4.3 it is shown that the ZnO/TiO2 interface plays a key role in enhancement of photodecomposition of MB under 400 nm illumination. The increase of photocatalytic activity was attributed to the shift of absorption edge of ZnO/TiO2 towards visible light in comparison to that of the ZnO(core)-etched TiO2. Further enhancement of photocatalytic activity of ZnO/TiO2 was achieved through its additional calcination at 450 °C for 3 h. This simple treatment brings 40% increase in the rate of MB decomposition and a two-fold rise of the photocurrent in H2O oxidation. Measurements of open circuit potential (VOC) showed that the improved properties of additionally calcined ZnO/TiO2 composites stem from the decrease of electron-hole recombination rate. STEM (Scanning Transmission Electron Microscopy) studies showed that the additional calcination resulted in formation of voids at the ZnO/TiO2 interface. EDX (Energy Dispersive X-ray) analysis and XPS (X-ray Photoelectron Spectroscopy) results proved that formation of voids is accompanied by the outward diffusion of Zn ions into TiO2 layer and allowed to conclude about the existence of the Kirkendall effect at ZnO/TiO2 interface. Occurrence of this effect observed for the first time at unusually moderate temperature (450 °C) was shown and attributed to a highly defective nature of the surface layer of the ZnO nanorods.
In the last chapter (Chapter 4.4), the composites consisting of ITO-supported ZnO nanorods covered with nitrogen-doped titanium dioxide, TiO2(N), shell were decorated with gold nanoparticles (Au NPs) in order to improve their photocatalytic activity under visible light. The photocatalytic properties of ZnO/TiO2/Au and ZnO/TiO2(N)/Au ternary composites were studied under illumination with Xe lamp equipped with a
400 nm cut-off filter. It was found that low Au NPs loading (0.37% at.) resulted in 60% enhancement of photocatalytic decolorization of MB under visible light with respect to the Au-free sample owing to plasmonic effects. Also, a simultaneous N-doping and Au NPs-decoration allows to multiply by three the photocurrent in photoelectrochemical water oxidation at the potential of 0.8 V vs. Ag/AgCl. It was also demonstrated that the Au-decorated composites possess a strong electrocatalytic activity in reduction O2 to active oxygen species (via formation of O2⦁– radicals) under a small negative bias
(–0.25 V vs. Ag/AgCl) in dark. Illumination of the polarized sample with visible light was shown to enhance this process resulting in rapid decomposition a model pollutant (MB) even in the presence of Na2SO4. This approach allows to completely overcome a problem of inhibition of the photocatalytic process by dissolved inorganic salts on non-polarized catalysts, thus meeting the aim of promising material for photoelectrocatalytic remediation of waste water, often containing a significant amount of inorganic ions.
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Rogé, Vincent. "Etude, fabrication et caractérisation de nanostructures catalytiques de type ZnO/SnO2 intégrées à des membranes modèles pour la dépollution de l'eau." Thesis, Strasbourg, 2015. http://www.theses.fr/2015STRAF046/document.
Повний текст джерелаАнотація:
La dépollution de l'eau est un des enjeux majeurs du XXIème siècle. Si différentes techniques de retraitement existent déjà, nous investiguons une nouvelle méthode associant les propriétés des membranes filtrantes à celles des matériaux photocatalytiques. Ainsi, nous avons étudié la croissance et l'activité photocatalytique de structures de type noyau/coquille de ZnO/SnO2 intégrées dans des membranes méso-poreuses (alumine poreuse) et macro-poreuses (fibres de verre). L'activité photocatalytique de ces matériaux a été évaluée sur des polluants modèles tels que le bleu de méthylène ou l'acide salicylique, mais aussi sur des polluants organiques identifiés dans les eaux de la rivière luxembourgeoise Alzette. L'impact environnemental des matériaux développés a été déterminé grâce a des analyses de cytotoxicité sur des cellules colorectales de type Caco-2, ainsi que sur des bactéries marines de type Vibrio FischeriWater treatment is one of the main challenge to overcome on the XXIst century. If many different techniques already exist, we investigate a new process associating the properties of porous membranes and photocatalytic materials. Thus, we studied the growth and photoactivity of core/shell structures of ZnO/SnO2 integrated into mesoporous (AAO) and macro-porous (glass fiber) membranes . The photocatalytic activity of these materials has been evaluated on organic pollutants like methylene blue or salicylic acid, but also on molecules found in the Luxembourgish Alzette river. The environmental impact of the synthesized structures has been determined with cytotoxic analyses on Caco-2 cells and Vibrio Fischeri bacteria
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Habba, Yamina Ghozlane. "Étude des nanostructures de ZnO pour leur application dans l'environnement : détection de gaz et dépollution de l'eau." Thesis, Paris Est, 2017. http://www.theses.fr/2017PESC1094/document.
Повний текст джерелаАнотація:
L’oxyde de zinc (ZnO) est un semi-conducteur II-VI remarquable et très prometteur dans le développement des nouveaux matériaux pour l’énergie renouvelable et pour l’environnement. ZnO est l’un des rares matériaux multifonctionnels. Grâce à ses nombreuses propriétés physiques, chimiques et optoélectroniques très intéressantes, lui confèrent d’être un matériau utilisé dans différents domaines d’applications telles que les cellules solaires, les diodes électroluminescentes, les capteurs de gaz, la dépollution de l’eau et de l’air par effet photocatalytique, etc.Dans cette thèse, nous nous sommes intéressés tout d’abords à optimiser l’élaboration de nanofils de ZnO (ZnO NWs) par méthode hydrothermale. Un procédé à deux étapes a été optimisé qui nous a permis d’obtenir des nanofils de ZnO ayant des excellentes propriétés morphologiques et structurales, avec une très bonne reproductibilité. Une nouvelle méthode d’élaboration, dite Electrospinning, a été mise au point. Ce procédé nous permet d’obtenir des micro- et nanofibres contenant des nanocristallites de ZnO. La combinaison des deux méthodes de synthèse nous a permis d’obtenir des nanostructures hiérarchiques de ZnO (NWs/NFs) possédant une surface effective beaucoup plus importante que la nanostructure classique (ZnO NWs).Deux applications ont été développées dans cette thèse. Dans un premier temps, des tests de détection de trois gaz réducteurs ont été réalisés sur les deux types de nanostructures de ZnO. Par la suite, une étude de purification de l’eau par effet photocatalytique a été réalisée sur un réseau de nanofils de ZnO sous irradiation UV pour les trois colorants (MB, MO et AR14). Afin d'améliorer la performance de la photocatalyse, deux nouvelles méthodes ont été développées. La première consiste à mettre en place un système microfluidique en utilisant des microréacteurs contenant des nanofils de ZnO comme photocatalyseur permettant ainsi à raccourcir considérablement le temps de dépollution. La seconde méthode est basée sur un procédé de dopage de ZnO permettant ainsi d’améliorer l'efficacité de la photocatalyseZinc oxide (ZnO) is a remarkable and very promising wide-gap II-VI semiconductor in the development of new materials for renewable energy and for the environment. Thanks to its many interesting physical, chemical and optoelectronic properties, this multifunctional material is used in many application fields such as solar cells, light emitting diodes, gas sensors, and water & air purification by photocatalytic effect, etc.In this thesis, we were interested in optimizing the synthesis of ZnO nanowires (ZnO NWs) by hydrothermal method. A two-step process has been optimized allowing us to obtain ZnO NWs having excellent morphological and structural properties, with very good reproducibility. A new synthesis method “Electrospinning” has been developed and the micro- & nanofibers containing ZnO nanocristallites can be obtained by this process. The combination of the two synthesis methods results a hierarchical nanostructure of ZnO (NWs/NFs) with an effective surface much larger than the classical one (ZnO NWs).Two applications have been developed in this thesis. Firstly, three reducing gases sensing tests have been carried out on the two types of ZnO nanostructures. Then, a photocatalytic water purification study has been carried out on a ZnO nanowire array under UV irradiation for the three dyes (MB, MO and AR14). In order to improve the photocatalysis performance, two new methods have been developed. The first is to set up a microfluidic system using microreactors containing ZnO NWs as a photocatalyst, thus the depollution time has been considerably shortened. The second method is based on the ZnO doping in order to improve the photocatalysis efficiency
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Espindola, Juliana da Silveira. "Produção fotocatalítica de hidrogênio a partir de soluções de etanol em água." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2010. http://hdl.handle.net/10183/26038.
Повний текст джерелаАнотація:
O presente trabalho tem o objetivo de investigar a obtenção de hidrogênio a partir de soluções de etanol em água, por fotocatálise, usando-se catalisadores a base de óxido de zinco (ZnO). Nestes estudos foram empregados cinco catalisadores ZnO, sendo um comercial e os demais preparados através de diferentes metodologias encontradas na literatura. Os catalisadores foram caracterizados por área BET, DRX e FRX, e a investigação preliminar da atividade destes catalisadores foi feita através de ensaios de degradação fotocatalítica de rodamina B em reator slurry em batelada, onde foram avaliadas a taxa de reação e a remoção de corante. Os ensaios para a produção fotocatalítica de hidrogênio foram realizados em um reator de quartzo, operado em batelada com catalisador em suspensão e atmosfera inerte de nitrogênio. A solução foi irradiada por uma série de seis lâmpadas compactas de luz negra. Ao longo dos testes, amostras das fases líquida e gasosa foram coletadas e analisadas para identificação do consumo de etanol e produção de hidrogênio usando-se, respectivamente, Carbono Orgânico Total (TOC) e Cromatografia Gasosa (GC). Resultados preliminares mostraram que os catalisadores ZnO comercial e sintetizado (ZnO Merck e ZnO-B) apresentam atividade fotocatalítica e desempenho similares aos do TiO2 para a degradação da rodamina B. Contudo, estes mesmos catalisadores mostraram-se pouco ativos para a produção fotocatalítica de hidrogênio, com desempenho bastante inferior ao do TiO2 nas mesmas condições. Foi possível observar que o maior rendimento em hidrogênio ocorre para baixas concentrações de catalisador (0,05 gL[elevado a potência menos]1) e elevadas concentrações de etanol, sendo pouco dependente do pH.This work aims to investigate the hydrogen production from ethanol-water solutions through photocatalysis, using zinc oxide catalysts (ZnO). Five ZnO catalysts were employed in this work; one was a commercial catalyst, while the others were prepared according to different methodologies reported in the literature. The catalysts were characterized by BET, XRD and XRF, and the preliminary investigation of their activity was done by photocatalytic degradation of rhodamine B, through the evaluation of the reaction rate and dye removal. Tests for photocatalytic hydrogen production were carried out in a quartz slurry batch reactor under nitrogen, irradiated by a set of six compact UV light bulbs. During the tests, gas and liquid samples were collected and analyzed in order to identify the consumption of ethanol and hydrogen production using, respectively, Total Organic Carbon (TOC) and Gas Chromatograph (GC). Preliminary results showed that the synthesized and commercial ZnO catalysts (ZnO-B and ZnO Merck) present photocatalytic activity and performance similar to TiO2 for the rhodamine B degradation. However, the ZnO catalysts presented lower performance when compared with TiO2 for hydrogen production, under the same conditions. It was observed that the highest hydrogen yield occurs for low concentrations of catalyst (0.05 gL1) and high concentrations of ethanol, being less dependent on pH.
Частини книг з теми "ZnO photocatalysis"
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Rose, T. L., and T. J. Lewis. "Adsorption and Decomposition of Dimethyl Methylphosphonate on ZnO And TiO2." In Photocatalysis and Environment, 690. Dordrecht: Springer Netherlands, 1988. http://dx.doi.org/10.1007/978-94-009-3015-5_32.
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Guo, Qin, Linqing Dai, Shenghui Guo, Libo Zhang, and Jinhui Peng. "Research on Microwave Roasting of ZnO and Application in Photocatalysis." In 7th International Symposium on High-Temperature Metallurgical Processing, 211–17. Cham: Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-48093-0_27.
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Oliveira, Marisa C., Nivaldo F. Andrade Neto, Renan Augusto Pontes Ribeiro, Mauricio R. D. Bomio, Fabiana V. Motta, and Sérgio Ricardo de Lázaro. "DFT Simulations for Heterogeneous Photocatalysis from ZnO and CuO Semiconductors." In Functional Properties of Advanced Engineering Materials and Biomolecules, 185–200. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-62226-8_6.
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Meshram, S. P., P. D. Jolhe, S. D. Shingte, B. A. Bhanvase, and S. H. Sonawane. "Sonochemical Synthesis of Mg-Doped Zno NPS For Efficient Sunlight Driven Photocatalysis." In Novel Water Treatment and Separation Methods, 47–60. Toronto ; Waretown, NJ : Apple Academic Press, 2017. | "Outcome of national conference REACT- 16, organized by the Laxminarayan Institute of Technology, Nagpur, Maharashtr , India, in 2016"--Introduction. || Includes bibliographical references and index.: Apple Academic Press, 2017. http://dx.doi.org/10.1201/9781315225395-4.
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Gurylev, Vitaly. "Case Study II: Defect Engineering of ZnO." In Nanostructured Photocatalyst via Defect Engineering, 189–222. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-81911-8_6.
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Chen, Jian-Tang, Mengshan Lee, and Walter Den. "Preparation of ZnO Photocatalyst by Plasma-Enhanced Vapor Deposition and Their Photocatalytic Activity." In ACS Symposium Series, 111–20. Washington, DC: American Chemical Society, 2014. http://dx.doi.org/10.1021/bk-2014-1184.ch006.
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Li, Likun, Junfu Chen, Jiann-Yang Hwang, JiXiong Liu, Yong Zhou, and Lijun Lu. "Photocatalytic H2Production Under Visible Light Irradiation on Novel Heterostructure NiS/ZnS Nanosheet Photocatalyst." In Characterization of Minerals, Metals, and Materials 2015, 777–84. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2015. http://dx.doi.org/10.1002/9781119093404.ch98.
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Li, Likun, Junfu Chen, Jiann-Yang Hwang, JiXiong Liu, Yong Zhou, and Lijun Lu. "Photocatalytic H2 Production under Visible Light Irradiation on Novel Heterostructure Nis/Zns Nanosheet Photocatalyst." In Characterization of Minerals, Metals, and Materials 2015, 777–84. Cham: Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-48191-3_98.
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Li, Xiu Yan, Ling Ke Zeng, Ping An Liu, Hui Wang, and An Ze Shui. "Photocatalytic Degradation of Methyl Orange on ZnO in Aqueous." In Key Engineering Materials, 1983–85. Stafa: Trans Tech Publications Ltd., 2007. http://dx.doi.org/10.4028/0-87849-410-3.1983.
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Wu, Daoxin, Changbin Xia, and Haixia Tong. "Study on Preparation of ZnO/TiO2and Its Photocatalytic Activity." In Supplemental Proceedings, 529–36. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2011. http://dx.doi.org/10.1002/9781118062173.ch66.
Повний текст джерелаТези доповідей конференцій з теми "ZnO photocatalysis"
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Mahmoud, Sawsan A., A. Abdel Aal, and Ahmed K. Aboul-Gheit. "Nanocrystalline ZnO Thin Film for Photocatalytic Purification of Water." In ASME 2008 2nd Multifunctional Nanocomposites and Nanomaterials International Conference. ASMEDC, 2008. http://dx.doi.org/10.1115/mn2008-47034.
Повний текст джерелаАнотація:
A thin film ZnO nanostructured catalyst exhibited a significantly greater superiority for the photodegradation of 2, 4, 6-TCP in water over photolysis via irradiation with UV of 254 nm wavelength. This ZnO photocatalyst was prepared via Zn metal evaporation and deposition on a glass sheet followed by calcination ature from 350 to 500 °C and the calcination time from 1 to 2h shows via SEM photography a decrease of ZnO nanoparticales sizes sheet followed by calcination (oxidation). Increasing the calcination temperature from 350 to 500 °C and the calcination time from 1 to 2h shows via SEM photography a decrease of ZnO nanoparticales sizes as well as the shape of their crystals finer needles, for which the crystallinity enhances as revealed by XRD. 2, 4, 6-Trichlorophenol was used as a model pollutant in water. Its photolysis using UV only or photocatalysis using UV irradiation in presence of the ZnO thin film catalyst indicated aromatic intermediates, which suffered of Cl by OH, addition of OH in a bare carbon in the aromatic ring, whereas in Photocatalysis deeper oxidation products, e.g., quinones and hydroquinones were also formed.
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Poliukhova, Valeriia, So-Hye Cho, and Anatolii Orlov. "ZnO-NiO Composites for Photocatalysis of Methylene Blue." In 2018 IEEE 38th International Conference on Electronics and Nanotechnology (ELNANO). IEEE, 2018. http://dx.doi.org/10.1109/elnano.2018.8477522.
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Bockute, Kristina. "Photoluminescence and structural defects of ZnO films deposited by reactive magnetron sputtering with unconventional Ar-O2 gas mixture formation." In SurfCoat Korea and Graphene Korea 2021 International Joint Virtual Conferences. Setcor Conferences and Events, 2021. http://dx.doi.org/10.26799/cp-surfcoat-graphene-korea-2021/1.
Повний текст джерелаАнотація:
ZnO is a well-known traditional industrial material which has high potential to become one of the key components for the next generation of future electronics, LED emitters, visible light photocatalysis and others. In its pristine form ZnO has relatively wide band gap of approximately 3.4 eV, but a lot of emerging applications requires some level of electronic structure engineering and structure optimisation. Studies show that ZnO properties strongly depend on the intrinsic defects type and concentrations. Both characteristics usually are depending on the synthesis method. Accordingly, there is great interest to develop new methods which would allow to obtain ZnO with optimised band gap and other properties. In current, study ZnO films were deposited using reactive magnetron sputtering with unconventional Ar-O2 gas mixture supply control: Ar flow was controlled to maintain total gas pressure at 1x10-2 mbar, whereas O2 flow rate was actively adjusted to maintain the selected intensity of optical zinc emission from the working cathode zone. Applying such ZnO formation method it was possible to stabilise reactive magnetron sputtering process over wide range of conditions. Elemental composition analysis by XPS revealed that despite large variations in Zn emission peak intensity within tested experimental conditions all films had nearly identical Zn:O ratios but at the same time their structural and optical properties differed significantly. The colour of the films varied from highly transparent yellowish-greenish, to intense orange, to opaque black. XRD analysis showed that films consisted of single polycrystalline wurtzite phase with varying orientations. PL spectroscopy analysis revealed that films had a lot of various defects including oxygen and zinc vacancies, interstitials and surface defects. Wide variation of ZnO properties obtained by different reactive sputtering conditions demonstrates the potential of the proposed method to control the formation of various intrinsic defects and to tailor their concentration.
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Ng, Dickon, and Jia Li. "Cotton-Derived C-doped ZnCo2O4/ZnO for Efficient Visible Light Photocatalysis." In 4th Annual International Conference on Materials Science, Metal & Manufacturing (M3 2017). Global Science & Technology Forum (GSTF), 2017. http://dx.doi.org/10.5176/2251-1857_m317.19.
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Mohammed, Mohammed, A. R. Rozyanty, Tijjani Adam, and Bashir O. Betar. "ZnO characterization, UV and photocatalysis mechanism for water repellent phenomena in polymer poly composite." In 3RD ELECTRONIC AND GREEN MATERIALS INTERNATIONAL CONFERENCE 2017 (EGM 2017). Author(s), 2017. http://dx.doi.org/10.1063/1.5002409.
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Liu, Z., G. L. Zheng, and M. J. Lin. "WO3-ZnO Supported on Molecular Sieves as Efficient Material for the Decolorization of Methylene Blue by Adsorption and Photocatalysis." In 2nd International Conference on Material Science, Energy and Environmental Engineering (MSEEE 2018). Paris, France: Atlantis Press, 2018. http://dx.doi.org/10.2991/mseee-18.2018.3.
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Pei, Carina Chun, Wallace Woon-Fong Leung, Lijun Yang, and Chi-ho Hung. "Photocatalytic Degradation of Rhodamine B by TiO2/ZnO Nanofibers Under Visible Light Irradiation." In ASME 2011 International Mechanical Engineering Congress and Exposition. ASMEDC, 2011. http://dx.doi.org/10.1115/imece2011-64695.
Повний текст джерелаАнотація:
Photocatalytic reduction of contaminants in wastewater or polluted water can be enhanced by finding a suitable catalyst with property that utilizes an extended light adsorption spectrum, reducing the recombination of electron-hole pairs, and casting the catalyst into a form with large surface-to-volume ratio to be in contact with the contaminants. Based on these objectives, Zn-doped TiO2 nanoparticles with high photocatalytic activity were synthesized by the sol–gel assisted nozzle-less electrospinning technique followed by calcining the precursor Ti(OiPr)4/ZnAc/PVP nanofibers in air in the temperature range of 450–650°. The thermal decomposition behavior was studied by thermogravimetric analyser and differential scanning calorimeter (TGA–DSC), and the morphology and crystal structure were monitored by scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). With the different concentration of zinc acetate in the precursor solution, the diameter of fibers ranged from 80–130 nm. The photocatalytic degradation of rhodamine B dye under visible light irradiation was also studied. It is found that the photosensitized degradation activity can be optimized by doping an appropriate amount of Zn (0.30 wt. %). Hence, the enhanced photodegradation of dyes with a new photocatalyst nanofiber under visible irradiation can be realized, which can take better use of solar energy.
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Zuo, Jinlong, Xue Li, Wei Jiang, Xinguo Yang, and Xuewei Wang. "Preparation of ZnO photocatalysts and study on photocatalytic degradation of antibiotic wastewater." In 2015 4th International Conference on Mechatronics, Materials, Chemistry and Computer Engineering. Paris, France: Atlantis Press, 2015. http://dx.doi.org/10.2991/icmmcce-15.2015.552.
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Khan, Talha Farooq, Mohsin Muhyuddin, Syed Wilayat Husain, and Muhammad Abdul Basit. "Synthesis and Characterization of ZnO-ZnS Nanoflowers for Enhanced Photocatalytic Performance : ZnS Decorated ZnO Nanoflowers." In 2019 16th International Bhurban Conference on Applied Sciences and Technology (IBCAST - 2019). IEEE, 2019. http://dx.doi.org/10.1109/ibcast.2019.8667220.
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Wei, Pengfei, Yao Li, and Xiaohong Yu. "Frabrication and Photocatalytic Performance of ZnO/ZnS Heterojunction Sheets." In Proceedings of the 2018 7th International Conference on Sustainable Energy and Environment Engineering (ICSEEE 2018). Paris, France: Atlantis Press, 2019. http://dx.doi.org/10.2991/icseee-18.2019.77.
Повний текст джерелаЗвіти організацій з теми "ZnO photocatalysis"
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Asenath-Smith, Emily, Emma Ambrogi, Eftihia Barnes, and Jonathon Brame. CuO enhances the photocatalytic activity of Fe₂O₃ through synergistic reactive oxygen species interactions. Engineer Research and Development Center (U.S.), September 2021. http://dx.doi.org/10.21079/11681/42131.
Повний текст джерелаАнотація:
Iron oxide (α-Fe₂O₃, hematite) colloids were synthesized under hydrothermal conditions and investigated as catalysts for the photodegradation of an organic dye under broad-spectrum illumination. To enhance photocatalytic performance, Fe₂O₃ was combined with other transition-metal oxide (TMO) colloids (e.g., CuO and ZnO), which are sensitive to different regions of the solar spectrum (far visible and ultraviolet, respectively), using a ternary blending approach for compositional mixtures. For a variety of ZnO/Fe₂O₃/CuO mole ratios, the pseudo-first-order rate constant for methyl orange degradation was at least double the sum of the individual Fe₂O₃ and CuO rate constants, indicating there is an underlying synergy governing the photocatalysis reaction with these combinations of TMOs. A full compositional study was carried out to map the interactions between the three TMOs. Additional experiments probed the identity and role of reactive oxygen species and elucidated the mechanism by which CuO enhanced Fe₂O₃ photodegradation while ZnO did not. The increased photocatalytic performance of Fe2O3 in the presence of CuO was associated with hydroxyl radical ROS, consistent with heterogeneous photo-Fenton mechanisms, which are not accessible by ZnO. These results imply that low-cost photocatalytic materials can be engineered for high performance under solar illumination by selective pairing of TMOs with compatible ROS.
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Chandler, Jackie, Joanne McKenzie, Isabelle Boutron, and Vivian Welch, eds. Cochrane Methods 2015. Wiley, October 2015. http://dx.doi.org/10.1002/14651858.cd201501.
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Chandler, Jackie, Joanne McKenzie, Isabelle Boutron, and Vivian Welch, eds. Cochrane Methods 2016. Wiley, October 2016. http://dx.doi.org/10.1002/14651858.cd201601.
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Hopewell, Sally, Mike Clarke, and Julian Higgins, eds. Cochrane Methods 2010. Wiley, October 2010. http://dx.doi.org/10.1002/14651858.cd201001.
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