Дисертації з теми "Platinum Dioxide"
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Chu, Yang. "Enhancement of Photocatalytic Activity by Site Poisoning Platinum Doped Titanium Dioxide." University of Akron / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=akron1417454495.
Повний текст джерелаBayrakceken, Ayse. "Platinum And Platinum-ruthenium Based Catalysts On Various Carbon Supports Prepared By Different Methods For Pem Fuel Cell Applications." Phd thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/12609448/index.pdf.
Повний текст джерелаPlatinum/MWCNT>
PlatinumBP2000. By means of the oxygen reduction reaction (ORR), the number of electrons transferred per oxygen molecule was calculated as 3.5, 3.6 and 3.7 for Platinum/BP2000, Platinum/VXR and Platinum/MWCNT, respectively. The microwave irradiation was used to prepare platinum on VX, Regal and BP2000 and platinum-ruthenium on VX. The effects of microwave duration, base concentration, carbon support used and surfactant/precursor ratios were investigated. The particle sizes of the catalysts were ranging between 2-6 nm. The prepared catalysts were characterized by XRD, XPS, and then PEMFC tests were performed. The performance was ordered as Platinum/VX>
Platinum/Regal>
Platinum/BP2000. The power losses arising from carbon dioxide in hydrogen feed were decreased by using prepared platinum-ruthenium based catalysts.
Ozcan, Ozlem. "Artificial Photosynthesis: Dye Assisted Photocatalytic Reduction Of Carbon Dioxide Over Pure And Platinum Containing Titania." Master's thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/12606313/index.pdf.
Повний текст джерела&ndash
bipyridyl) ruthenium (II) chloride hexahydrate) , BrGly (1,7-dibromo-N,N&rsquo
-(t-butoxycarbonyl-methyl)-3,4:9,10-perylene-diimide) and BrAsp (1,7-dibromo-N,N&rsquo
-(S-(1-t-butoxy-carbonyl-2-t-butoxycarbonyl-methyl)-ethyl)- 3,4:9,10-perylenediimide). Their SEM, XRD, UV-Vis spectroscopy and hydrogen chemisorption characterizations are performed. Reaction tests are performed for the catalysts under UV and visible light. The only quantifiable reaction product was methane. With RuBpy containing catalysts hydrogen production was observed under UV light, but not quantified. The results indicated that Pt addition resulted in higher yields in UV experiments. The presence of light harvesting molecules resulted in increase in photocatalytic activity for thin films, whereas it resulted in no change or decrease for the thick films. The latter case may occur due to the UV filtering effect of these dyes. Use of dyes (with visible range absorption bands) as promoters made visible light excitation possible. This resulted in photocatalytic activity under visible light, which was not observed with unpromoted and Pt promoted TiO2 thin film catalysts. Under visible light methane was the only quantified photoreduction product. CO evolution was also observed, but not quantified. The photocatalytic activities of the dye promoted TiO2 were in the order of RuBpy~BrAsp>
BrGly. The methane yields of visible light experiments were one order of magnitude lower than the ones under UV light.
Photinon, Kanokorn. "DEVELOPMENT OF DIMETHYL ETHER (DME) AND CARBON DIOXIDE SENSORS USING PLATINUM NANOPARTICLES AND THICK FILM TECHNOLOGY." Case Western Reserve University School of Graduate Studies / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=case1164899809.
Повний текст джерелаMotsegood, Perry Nelson. "Improved performance of alkaline batteries via magnetic modification and voltammetric detection of breath acetone at platinum electrodes." Diss., University of Iowa, 2012. https://ir.uiowa.edu/etd/4883.
Повний текст джерелаGrant, Ann W. "Surface studies of model catalysts using metal atoms and particles on ZnO(0001)-Zn and -O and TiO₂(110) /." Thesis, Connect to this title online; UW restricted, 2001. http://hdl.handle.net/1773/8499.
Повний текст джерелаFalch, Anzel. "Synthesis, characterisation and potential employment of Pt–modified TiO2 photocatalysts towards laser induced H2 production / Falch A." Thesis, North-West University, 2011. http://hdl.handle.net/10394/7346.
Повний текст джерелаThesis (M.Sc. (Chemistry))--North-West University, Potchefstroom Campus, 2012.
Soufi, Jihène. "Traitement des gaz d’échappement des groupes électrogènes alimentés par des gasoils, fuels marines ou bio-huiles : élimination des HAP en présence ou non de SOx." Thesis, Lyon, 2017. http://www.theses.fr/2017LYSE1120.
Повний текст джерелаPonczek, Milena 1986. "Degradação de compostos orgânicos voláteis em fase gasosa através da fotocatálise com luz UV, TiO2 e TiO2/Pt." [s.n.], 2014. http://repositorio.unicamp.br/jspui/handle/REPOSIP/266075.
Повний текст джерелаDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química
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Resumo: Compostos orgânicos voláteis, ou COV, são uma importante classe de poluentes do ar comumente encontrados na atmosfera ao nível do solo, nos centros urbanos e industriais. O tratamento de COV provenientes de fontes industriais através da fotocatálise heterogênea é uma técnica eficiente para a degradação de baixas concentrações de uma grande gama de compostos orgânicos diferentes (hidrocarbonetos, aromáticos, alcóois, cetonas, etc) operando em condições ambientes. Um dos problemas que ainda impede sua aplicação industrial é a desativação do catalisador e por isso muitos grupos de pesquisa têm se dedicado ao estudo desta técnica na tentativa de melhorá-la e solucionar estes entraves. A atividade fotocatalítica do TiO2 pode ser melhorada pela adição de metais na sua superfície. Neste trabalho, preparou-se catalisadores de TiO2 por impregnação de Pt (1% m/m). A platina foi reduzida com NaBH4, fazendo-se posteriormente caracterização por DRX, XPS, UV ¿Vis, BET, Quimissorção de H2 e MEV/EDS para a validação do método de síntese. Todas as técnicas confirmaram que o método de redução com NaBH4 não modifica estruturalmente o TiO2, mantendo a sua cristalinidade e a razão de anatase/rutilo. A técnica de XPS indicou a presença de metal em estado de oxidação reduzido. Para o estudo da influência da impregnação de Pt no óxido titânio, foram realizados experimentos de fotocatálise em um reator recoberto com TiO2puro, e em um reator recoberto com TiO2/Pt variando-se a concentração de entrada (de 50 à 500 ppmv) ou o tempo de residência (de 10 à 50 s) para os COV n-octano, iso-octano, n-hexano e ciclohexano. Utilizou-se reatores tubulares com volume interno de 1160 ml com os catalisadores, dióxido de titânio puro ou modificado, imobilizados na parede interna dos reatores. A fonte de radiação UV foi uma lâmpada do tipo germicida de 100W de potência, caracterizada por comprimentos de onda de 254 nm (banda de emissão UV-C). As concentrações na entrada e na saída do reator foram analisadas através de um monitor contínuo de hidrocarbonetos do tipo FID. A adição de platina ao TiO2 gera uma melhoria na eficiência fotocatalítica nas reações de oxidação de COV; a conversão dos COV utilizando o catalisador impregnado com platina atingiu 99 % de conversão, enquanto que TiO2 puro atingiu, no máximo 93%
Abstract: Volatile organic compounds, or VOC, are an important class of air pollutants commonly found in the atmosphere at ground level in urban and industrial centers. The treatment of VOC from industrial sources by oxidative photodegradation is presented as a good alternative. These systems are promising as pollution control technology, since they can decompose low concentrations of VOC efficiently and in ambient conditions. The recombination of electrons and holes formed on the surface of TiO2 is a factor that limits the photocatalytic efficiency. For this reason, many efforts have been made to maximize the separation of charges, in order to improve the photocatalytic efficiency. A proposed alternative is to add noble metals to TiO2 structure. This work aims to study the degradation of volatile organic compounds by heterogeneous photocatalytic oxidation using ultraviolet light, bare TiO2 and TiO2 impregnated with 1% w/w platinum as catalysts. TiO2 catalysts were prepared by impregnating Pt on TiO2 structure by reduction method with NaBH4. The photocatalysts were characterized using analytical techniques like XRD, XPS, UV-Vis Diffuse Reflectance, BET, H2 Chemisorption and SEM/EDS to validate the method of synthesis. All analysis confirmed that the reduction method with NaBH4 do not structurally modify TiO2, keeping its crystallinity and the ratio of anatase/rutile. XPS indicates the presence of metal in reduced oxidation state. To study the influence of the impregnation of platinum on titania, after synthesis and characterization, the study of gas-solid heterogeneous photocatalytic oxidation of some VOC was carried out at room temperature with annular plug flow reactors (1160 ml), one coated with pure TiO2 and another coated with TiO2/Pt, the catalysts were immobilized on reactor¿s internal walls. The photocatalystic tests were performed for n-octane , iso-octane, n-hexane and ciclohexane varying the inlet concentration (from 50 to 500 ppm) or residence time (from 10 to 50 s). The light source was an UV lamp (100 W, wavelengths with a maximum intensity at 254 nm. Reactants and products concentrations were analyzed using a continuous monitoring with a total hydrocarbon analyzer with flame ionization detector (FID). The addition of platinum to TiO2 improves photocatalytic efficiency of oxidation of VOC; conversion of the VOC using impregnated catalyst reached 99%, whereas pure TiO2 was at most 93%. No título do trabalho, a fórmula TiO2 deve vir com o "2" em subscrito, pois trata-se da fómula química da substância
Mestrado
Processos em Tecnologia Química
Mestra em Engenharia Química
Modingwane, Boitshoko Goitseone. "Investigation of Pt supported on carbon, ZrO2, Ta2O5 and Nb2O5 as electrocatalysts for the electro–oxidation of SO2 / Boitshoko Goitseone Modingwane." Thesis, North-West University, 2011. http://hdl.handle.net/10394/5557.
Повний текст джерелаThesis (M.Sc. (Chemistry))--North-West University, Potchefstroom Campus, 2011.
NAKAMURA, LIANA K. O. "Atividade fotocatalítica de filmes nanoestruturados de dióxido de titânio incorporados com nanopartículas de metais nobres." reponame:Repositório Institucional do IPEN, 2012. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10170.
Повний текст джерелаMade available in DSpace on 2014-10-09T14:04:01Z (GMT). No. of bitstreams: 0
Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
Großmann, Katharina [Verfasser]. "Detection mechanism of reducing gases and influence of water on tin dioxide based gas sensors : Differences in surface chemistry between undoped and platinum doped materials / Katharina Großmann." Aachen : Shaker, 2013. http://d-nb.info/1051575494/34.
Повний текст джерелаBarroo, Cédric. "Processus non-linéaires au cours de l'hydrogénation du NO2 sur catalyseurs à base de platine et de rhodium." Doctoral thesis, Universite Libre de Bruxelles, 2014. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/209252.
Повний текст джерелаDoctorat en Sciences
info:eu-repo/semantics/nonPublished
Ferrandon, Magali. "Mixed metal oxide - noble metal catalysts for total oxidation of volatile organic compounds and carbon monoxide." Doctoral thesis, Stockholm, 2001. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3156.
Повний текст джерелаDRESCH, MAURO A. "Aplicação de catalisadores PtSn/C e membranas Nafion-SiOsub(2) em células a combustível de etanol direto em elevadas temperaturas." reponame:Repositório Institucional do IPEN, 2014. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10633.
Повний текст джерелаMade available in DSpace on 2014-10-09T14:01:33Z (GMT). No. of bitstreams: 0
Tese (Doutorado em Tecnologia Nuclear)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
Kaczmarek, Thibault. "Impact des éléments platinoïdes et du molybdène dans les mécanismes de dissolution du dioxyde d'uranium." Thesis, Université de Montpellier (2022-….), 2022. http://www.theses.fr/2022UMONS014.
Повний текст джерелаAlthough a spent nuclear fuel is composed of about 96 wt. % of UO2, its composition and microstructure display an extreme complexity due to the presence of more than 30 fission products. Fission products found as metallic precipitates are mainly composed of the noble metals Ru, Rh, Pd, Mo (platinium group metals = PGM's). The first step of the spent nuclear fuel reprocessing is the dissolution in a concentrated nitric acid solution. In this context, this Ph. D. work focuses on the impact of these elements on the kinetics of dissolution of the UO2 matrix. Model samples of UO2 incorporating 3 mol. % of Ru, Rh, Pd or Mo were prepared using a wet chemistry route, then were sintered at high temperature under reducing atmosphere. The speciation, morphology as well as the spatial distribution of the elements in the sintered samples were determined. The pellets exhibited similar microstructure. Then, the synthesized samples were submitted to dissolution tests in order to quantify the impact of the presence of the metallic particles on the dissolution rate of UO2. Dissolution experiments were carried out under conditions representative of the reprocessing of SNF. The dissolution rate of each model compound was determined at macroscopic scale and compared to that of UO2. At microscopic scale, the evolution of the solid/liquid interface was monitored by MEBE. Additionally, specific dissolution experiments were designed to identify the mechanisms involving these elements. The obtained results allows to compare the influence of each element of interest and to improve our understanding of their specific role during the dissolution of UO2 in nitric acid. dissolution in a hydrochloric medium will also be carried out to erase the impact of nitrate ions on the dissolution
Chen, Hsiao-Hui. "Formation of low temperature silicon dioxide films using chemical vapor deposition /." Online version of thesis, 1991. http://hdl.handle.net/1850/11160.
Повний текст джерелаTaimoor, Aqeel Ahmad. "Biogas valorization for chemical industries via catalytic process." Thesis, Lyon 1, 2010. http://www.theses.fr/2010LYO10243/document.
Повний текст джерелаHydrogen potential from biomass is currently being studied but ways of valorization of such biogas (H2/CO2 mix) via catalytic reaction, other than simply burning has not yet been considered. Thus the main objective of this work is the exploration of such methods. Effect of CO2 over catalytic system was not well known and only hydrogen dissociation inhibition is reported. Toluene hydrogenation over Pt catalyst is studied and activity loss transition behavior is observed with no CO2 where as complete catalyst inactivity for toluene hydrogenation is found in presence of CO2. Catalyst surface change by CO2 is quantified by DRIFT analysis and two-site mechanism is found to prevail. Reverse water gas shift reaction producing CO is found to be the main cause behind such catalyst surface response to CO2. Adsorption competition between CO and carboxylic acids is exploited for selectivity shift in favor of acids conversion. Alumina support is fouled by carbonates complexes with CO2 while silica is reported to promote decomposition, thus both were rejected and titanium oxide is used instead with a range of products produced. The required selectivity shift between reverse water gas shift and acid conversion is thus observed. Less active iron oxide catalyst further suppresses CO2 conversion. Iron oxide surface chemistry plays an important role over product selectivity among ketones and aldehydes. Two sites mechanism still prevails over iron and stable continuous operation requires simultaneous iron reduction via hydrogen, if totally oxidized by CO2–a reaction product, will cease to produce ketones. Energetically the process devised for acetone production is self sufficient and acetone not only act as an energy storage molecule but can also compensate new phenol production process producing no acetone
Ali, Abdulkahhar. "Etudes electrochimique et chromatographique de la photooxydation des alcools primaires aliphatiques sur des suspensions de catalyseurs a base de dioxyde de titane." Poitiers, 1988. http://www.theses.fr/1988POIT2262.
Повний текст джерелаNeogi, Sudarsan. "Chemical vapor deposition of silicon dioxide thin films for composite thermo-oxidative durability." Ohio : Ohio University, 1992. http://www.ohiolink.edu/etd/view.cgi?ohiou1173753842.
Повний текст джерелаTengsuwan, Siwach. "Environmentally-benign Electroless Nickel-Phosphorus Plating on Thermoplastic Polymers using Co-polymer based Hydrophilic Modification and Supercritical Carbon Dioxide Pd-complex Infusion." 京都大学 (Kyoto University), 2014. http://hdl.handle.net/2433/188620.
Повний текст джерелаPeronio, Angelo. "A closer look at heterogeneous catalysis: reaction intermediates at the single-molecule level." Doctoral thesis, Università degli studi di Trieste, 2013. http://hdl.handle.net/10077/8577.
Повний текст джерелаThe present work pertains to the surface science approach to heterogeneous catalysis. In particular model systems for CO2 hydrogenation to methanol, and NO selective catalytic reduction, are investigated by means of a combined approach, where the molecular-level insight provided by a low-temperature scanning tunneling microscope is complemented by density functional theory (DFT) calculations of their electronic structure. To this end, the Inelastic Electron Tunneling Spectroscopy (STM-IETS) technique was introduced for the first time in our laboratory, a recent development which allows to measure the vibrational spectrum of individual molecules adsorbed on a surface. Regarding CO2, we provide single molecule imaging and characterization of CO2/Ni(110), chemisorbed with high charge transfer from the substrate, in an activated state that plays a crucial role in the hydrogenation process. We obtain a detailed characterization of the adsorption geometries and an estimate of the energies corresponding to the different adsorbed states. A consistent picture of CO2 chemisorption on Ni(110) is provided on the basis of the newly available information, yielding a deeper insight into the previously existing spectroscopic and theoretical data. In the Selective Catalytic Reduction (SCR) process, nitrogen oxide is selectively transformed to N2 by reductants such as ammonia. The specificity of this reaction was tentatively attributed to the formation of NH3-NO coadsorption complexes, as indicated by several surface science techniques. Here we characterize the NH3-NO complex at the atomic scale on the (111) surface of platinum, investigating the intermolecular interactions that tune the selectivity. The structures that arise upon coadsorption of NH3 and NO are analyzed in terms of adsorption sites, geometry, energetics and charge rearrangement. An ordered 2 × 2 adlayer forms, where the two molecules are arranged in a configuration that maximizes mutual interactions. In this structure, NH3 adsorbs on top and NO on fcc-hollow sites, leading to a cohesional stabilization of the extended layer by 0.29 eV/unit cell. The calculated vibrational energies of the individually-adsorbed species and of the coadsorption structure fit the experimental values found in literature within less than 6%. The characterizations and optimizations that had to be tackled in order to successfully perform STM-IETS measurement are eventually presented, focusing in particular on an original method which allows to increase the achieved resolution. Namely, the modulation broadening associated to phase-sensitive detection is reduced by employing a tailored modulation function, different from the commonly-used sinusoid. This method is not limited to STM-IETS, but can be easily applied whenever a lock-in amplifier is used to measure a second derivative.
XXV Ciclo
1984
Jordaan, Ilse. "Persistent organic pollutants (POPs) associated with a platinum mine in the Limpopo Province, South Africa / Ilse Jordaan." Thesis, North-West University, 2005. http://hdl.handle.net/10394/995.
Повний текст джерелаThesis (M. Environmental Science)--North-West University, Potchefstroom Campus, 2006.
Bertin, Thierry. "Elimination par voie catalytique des oxydes d'azote émis lors du fonctionnement des moteurs "Diesel" et des moteurs "essence mélange pauvre"." Poitiers, 1998. http://www.theses.fr/1998POIT2260.
Повний текст джерелаUrfels, Laetitia. "Oxydation du méthane à basse température sur des catalyseurs à base de métaux précieux : application à l'échappement des véhicules GNV fonctionnant en mélange pauvre." Lyon 1, 2003. http://www.theses.fr/2003LYO10088.
Повний текст джерелаMontméat, Pierre. "Rôle d'éléments métalliques sur les mécanismes de détection d'un capteur de gaz à base de dioxyde d'étain. Application à l'amélioration de la sélectivité à l'aide d'une membrane de platine." Phd thesis, Ecole Nationale Supérieure des Mines de Saint-Etienne, 2002. http://tel.archives-ouvertes.fr/tel-00125693.
Повний текст джерелаLe dépôt d'un film mince de platine sur une couche épaisse de 20 μm de dioxyde d'étain a permis d'améliorer la sélectivité du dispositif au CH4 en présence de C2H5OH et de CO. En revanche, lorsqu'il a été déposé à la surface d'une couche mince de 70 nm de dioxyde d'étain, le film mince de platine n'a pas rendu possible l'amélioration de la sélectivité du matériau sensible.
Par la suite, notre démarche a consisté à évaluer les propriétés physico-chimiques de chaque constituant du dispositif à savoir le dioxyde d'étain, le métal ou l'association des deux. Pour cela, nous avons fait appel à différentes techniques couramment utilisées pour la caractérisation des interactions gaz – solide telles que la catalyse, la calorimétrie ou la mesure électrique. Des effets de synergie entre le métal et l'oxyde vis-à-vis de l'adsorption et des effets électriques de l'oxygène gazeux ont pu être mis en évidence. Ces résultats ont été exploités pour proposer un mécanisme permettant d'expliciter les phénomènes électriques qui interviennent lors de la chimisorption d'oxygène à la surface d'un système regroupant le dioxyde d'étain et un métal. Ce modèle a été confronté aux résultats expérimentaux relatifs à l'influence de l'épaisseur du dioxyde d'étain sur les réponses électriques sous gaz réducteur des capteurs de gaz.
Taimoor, Aqeel Ahmad. "Valorisation de biogaz pour industrie chimie par voie catalytique." Phd thesis, Université Claude Bernard - Lyon I, 2010. http://tel.archives-ouvertes.fr/tel-00881030.
Повний текст джерелаFarias, Manuel de Jesus Santiago. "Eletrooxidações de acetaldeído comum e etanol isotopicamente marcado (H3 13C-12CH2OH) em superfície de platina policristalina acompanhadas por FTIRS in situ." Universidade Federal do Maranhão, 2006. http://tedebc.ufma.br:8080/jspui/handle/tede/1561.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
This is work treat of the acetaldehyde and labeled ethanol oxidations, both kinds in percloric acidic medium, 0,1 Mol L-1 HClO4 on the Pt polycrystalline surface with used conventional electrochemical and spectroscopy techniques (FTIRS in situ). From acetaldehyde, wanted to find the mean concentration that better favor the reaction to evolve for CO2 in the potential smaller from production of the kind. The concentration 0,01 Mol L-1 was better suitable, but the increase of the concentration in solution, this is pathway was whole inhibited. However, in the high potential the form to acetic acidic is favorable. For main cronoamperometry, acetaldehyde in the concentration 0,02 Mol L-1, were able proof results in situ FTIRS. According to potential, this is results was interpreted second pattern to consider: the pear adsorbed kinds (Langmuir-Hinshelwood) and other where consider only one adsorbed kinds between adsorbed (pattern Eley-Rideal mechanism). In the case of ethanol labeled oxidation (H3 13CO 12CH2OH), it is search to look into the path delineated from way severous of the reaction from to form CO2. The results showed that is product would to be results of the intermediates oxidations contained carbon from alcohol group and intermediates contained carbon from group methyl; however, the intermediates contained carbon alcohol group is mores able reactive in the zone potential searched in the work, is this mores, confronted with able reactive metil group. The path double that yield CO2 in the zone potential below 1,0 V, are yielded coupling bands 12COL and 13COL which coexist in below potential. In the presence kind 13COL in 0,4 V potential proof that of the efficiency of the platinum electrode for the oxygenation group metil in the zone below potential. In the potential largest that 1,0 V, where exist the formation continuous of carbon dioxide, the difference in the greatness bands associated from 12CO2 e 13CO2 (double path product contained carbon), was interpreted in the sense of the electrochemical conditions infortunable for remover hydrogen group metil; additional this is kind was to promote for yield from molecules, which not is able identify for whole technique.
Este trabalho trata das reações de eletrooxidações de acetaldeído comum e etanol isotopicamente marcado, ambas reações em superfície de platina policristalina em meio de ácido perclórico, HClO4, 0,1 Mol L-1, com a utilização de técnicas eletroquímicas convencionais e espectroscopia (FTIRS in situ). Para o acetaldeído, essa reação foi estuda com a dependência do potencial aplicado e a concentração do aldeído em solução, que melhor resultaram na transformação desta molécula a CO2. Assim, para o potencial 0,6 V, a concentração de aldeído 0,01 Mol L-1 foi a mais apropriada deduzida a partir de FTIRS in situ e, a concentração 0,02 Mol L-1 permitiu a geração de maior densidade de corrente e foi inferida a partir de cronoamperometria. Essa discrepância foi discutida em termos das reações específicas que resultam no sinal analítico para cada técnica. Dependendo da concentração do acetaldeído, a via de formação de CO2 foi completamente inibida e, em altos potenciais, prevalecia sempre a formação de ácido acético. Paralelamente, dependendo do potencial, estes resultados foram interpretados com base em modelos de mecanismos de reações que considera: um par de reagentes adsorvidos (mecanismo Langmuir-Hinshelwood) e apenas uma espécie adsorvida do par fundamental de reagentes (mecanismo Eley-Rideal). Para o etanol isotopicamente marcado (H3 13C 12CH2OH), foram investigados passos delineados pelas diferentes vias de reação de formação de CO2. Os resultados mostraram que este produto pode ser resultante da eletrooxidação de intermediários contendo o carbono do grupo álcool e do grupo metil, sendo que o intermediário contendo o carbono do grupo álcool, para toda a faixa de potenciais investigados, é bem mais reativo que o intermediário contendo o carbono do grupo metil. As vias duplas que geram CO2 em potenciais abaixo de 1,0 V são resultantes de bandas acopladas de 12COL e 13COL que coexistem em baixos potenciais. A presença de 13COL em 0,35 V foi encarada como uma evidência da eficiência da Pt para oxigenação do grupo metil em baixos potenciais. Em potenciais acima de 1,0 V, onde há produção contínua de dióxido de carbono, a diferença na magnitude das intensidades de bandas relativa ao 13CO2 e 12CO2 (das vias de origem de carbono), foi interpretada como sendo as referidas condições eletroquímicas desfavoráveis para desprotonação do metil.
Savych, Maciejasz Juliia. "Synthèse et caractérisation de nanocomposites platine/nanofibres pour électrodes de pile à combustible à électrolyte polymère." Thesis, Montpellier 2, 2014. http://www.theses.fr/2014MON20152/document.
Повний текст джерелаThe objective of this thesis is to develop corrosion resistant catalyst support materials that can potentially replace carbon in Polymer electrolyte fuel cells. Therefore, Nb doped TiO2 and SnO2 nanofibres and nanotubes were prepared by electrospinning and characterised by X-ray diffraction, X-ray photoelectron spectroscopy, Raman spectroscopy, N2 adsorption/desorption analysis and electronic conductivity measurements. The obtained Nb doped TiO2 and SnO2 one dimensional structures demonstrated higher conductivity and surface area than non-doped oxides. Pt nanoparticles were prepared using a modified microwave-assisted polyol method and deposited on the electrospun supports. Electrochemical characterisation of the obtained electrocatalysts was performed ex situ using a rotating disc electrode, and compared with a commercial carbon support (Vulcan XC-72R). Pt supported on Nb doped SnO2 provided higher electrochemical stability in comparison to Pt on carbon. Thus, a cathode of Pt/Nb-SnO2 prepared by spray-coating was integrated into Membrane Electrode Assembly (MEA) and characterised in situ in single Polymer electrolyte fuel cell. The MEA exhibited higher durability though lower power density compared to MEA with Pt/C based cathode. Sb doped SnO2 nanotubes have higher conductivity than Nb doped material and when integrated into a cathode, provided enhanced power density in comparison to Nb-SnO2 based cathode
Roth, Delphine. "Catalyseurs à base de métaux nobles pour l'oxydation totale du méthane : application au traitement des effluents des moteurs fonctionnant au gaz naturel." Lyon 1, 2000. http://www.theses.fr/2000LYO10113.
Повний текст джерелаTsai, Ya-Han, and 蔡雅涵. "Development of Nanosized-Platinum Deposited Titanium Dioxide for Electroanalytical Applications." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/4bpv2d.
Повний текст джерела國立中興大學
化學系所
101
The thesis is divided into two major parts. The first part focuses on the development of composite platinum nanoparticles -titanium dioxide (PtNP/TiO2) and the second part deals with its application as an electrochemical sensor. We use hexachloroplatinic acid solution (H2PtCl6) as a precursor in photo- reduction of platinum nanoparticles on TiO2. In order to understand the best condition for the fabrication of PtNP/TiO2, the influences of pH values, Pt and titanium dioxide concentration were investigated. Both Transmission Electron Microscopy (TEM) and Energy Dispersive Spectrometer (EDS) studies were used to analyze the morphology as well as the size of Pt nanoparticles deposited on TiO2. Well-defined Pt nanoparticles with the size of ~5 nm were distributed on the surface of TiO2 as confirmed from the TEM images. Previous works addressed about the preparation of platinum nanoparticles on TiO2, with the addition of reducing reagents (like NaBH4 and sodium citrate) or organic solvents in the process, some methods even need heating to accelerate the reduction rate of metal nanoparticles, and also use complicated process of annealing or calcination at high temperature for making platinum nanoparticles on the surface of TiO2. Compared to these works, the advantages of our proposed method are no complicated process involved or heating while in the preparation step without the addition of any reducing agents. The second part of this study aimed at the electrochemical applications of the PtNP/TiO2. The PtNP/TiO2 modified screen-printed carbon electrode (PtNP/TiO2-SPCE) displayed good electrocatalytic ability for dissolved oxygen (DO) measurement and the direct electrochemical oxidation of glucose. The DO measurement by the PtNP/TiO2-SPCE displayed good linearity with that of a commercial DO meter indicating that the proposed system can be used as a promising O2 sensor. Besides, combination of the PtNP/TiO2-SPCE and amperometry was used for the determination of glucose. The calibration plot was obtained in the range of 10 μM-3 mM glucose (r2 = 0.998) with a sensitivity of 20.084 μA mM–1 cm–2 and the lowest detection limit of 0.46 μM (S/N = 3). And this detection method could avoid the interference of the interferant such as Uric acid, L(+)-Ascorbic acid, and Acetaminophen. Overall, we present a simple method for the preparation of titanium dioxide supported platinum catalyst for use as a sensor with good sensitivity, wide linear range, and good stability, showing excellent electrocatalytic activity and practicability towards detection of both O2 and glucose.
Li, Chien-Jen, and 李健仁. "Molecular Dynamics simulation of Carbon Dioxide adsorption on graphite and platinum surfaces." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/dhtrgt.
Повний текст джерела國立臺北科技大學
製造科技研究所
96
This study puts CO2 in the system which affiliation two piece of flake graphite limit. To change 5 kind of surface energy (ε*=1、1.58、2.24、3.16、4.47),3 kind of temperature(240K、260K、280K) and 3 kind of density(ρ*=0.293、0.39、0.44). The results show that more CO2 change liquid from gas in surface energy is 4.47,the lowest temperature is 240K, and the highest density is 0.44. In this system, the adsorption is controlled by adsorptive energy at boundary, escaptive energy of temperature, and variation of density. We also puts CO2 in two piece of Pt limit to compare different between graphite and Pt. The results show that kinetic energy was increased with Τ*.
Kuo, Chia-Hsun, and 郭佳勳. "Effect of Gold on Platinum Catalyst for Carbon Dioxide Reforming of Methane Reaction." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/37043204484130659671.
Повний текст джерелаCHUANG, YI-HSUAN, and 莊易軒. "Fabrication of Phosphorene Modified Titanium Dioxide Photoelectrode and Silver Modified Platinum Counter Electrode for Dye-sensitized Solar Cells under Low Illumination." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/9ask5v.
Повний текст джерела國立雲林科技大學
電子工程系
106
In this study, phosphorene was mixed with titanium dioxide (TiO2) colloid and deposited on fluorine-doped tin oxide (FTO) conductive substrate by doctor blade method as the photoelectrode of dye-sensitized solar cell (DSSC). The reason is because phosphorene has high electron mobility and high absorption, which could enhance the electron transfer ability and increase the recombination resistance, thus improve the current density. The surface morphology of phosphorene film was characterized by field-emission scanning electronic microscopy (FE-SEM). The optical absorption of phosphorene-TiO2 composited film was measured by UV–visible spectrometer. The interface resistance of DSSC was measured by electrochemical impedance spectroscopy. Compared with the photovoltaic conversion efficiency of 3.50% based on pure TiO2 photoelectrode, it is found that the optimal photovoltaic conversion efficiency of 4.35% is achieved when the phosphorene is introduced to TiO2 photoelectrode, and the efficiency increases by 24%. More than that, silver (Ag) was deposited by radio frequency sputtering to modify the conventional platinum (Pt) counter electrode to enhance the redox reaction between electrolyte and dye molecule. The reason is because Ag has the highest electrical conductivity in metal, and the lattice strain effect will increase the surface absorption ability of film. The silver modified Pt counter electrode with different Ag thicknesses was investigated for electrical conductivity and catalytic activity. The surface morphology of Pt/Ag counter electrode was characterized by FE-SEM. The sheet resistance of Pt/Ag counter electrode was measured by 4-point probing system. The interface resistance of DSSC was measured by electrochemical impedance spectroscopy. Compared with the pure Pt counter electrode, the silver modified Pt counter electrode can provide a higher electrical conductivity and a superior catalytic activity. Moreover, the photovoltaic conversion efficiency of DSSC can be enhanced from 3.82% with the Pt counter electrode to 4.46% with the Pt/Ag counter electrode, and the efficiency increases by 16%. Finally, the DSSC of optimal composited films with phosphorene-TiO2 photoelectrode and Pt/Ag counter electrode was investigated under low illumination. The photovoltaic conversion efficiency of the DSSC can be enhanced from 4.76% under illumination of 100 mW/cm2 to 7.21% under illumination of 1.75 mW/cm2 and the efficiency increases by 52%.
Kuvarega, Alex Tawanda. "Photocatalytic performance of nitrogen-platinum group metal co-doped Tio2 supported on carbon nanotubes for visible-light degradation of organic pollutants in water." Thesis, 2013. http://hdl.handle.net/10210/8533.
Повний текст джерелаElimination of toxic organic compounds from wastewater is currently one of the most important subjects in water-pollution control. Among the many organic pollutants are dyes and emerging pollutants such as natural organic matter (NOM). Dyes such as Eosin Yellow (EY), an anionic xanthene fluorescent dye, can originate from many sources such as textile industrial processes, paper pulp industries and agricultural processes. Most dyes are problematic because they are resistant to conventional chemical or biological water-treatment methods and therefore persist in the environment. NOM consists of a highly variable mixture of products found in water and soils. NOM is formed as a result of the decomposition of plant and animal material and is a precursor to the formation of disinfection by-products (DBP) during water disinfection. These organic compounds cause undesirable colour, taste and odour in water. NOM affects the capacity of other treatment processes to effectively remove organic micro-pollutants or inorganic species that may be present in the water. Its removal also uses up chemicals and energy and so it is expensive to treat. Titanium dioxide (TiO2) has emerged as one of the most fascinating materials in the modern era due to its semiconducting and catalytic properties. TiO2 is a large band-gap semiconductor that exists mainly in the anatase (band gap 3.2 eV) and rutile (band gap 3.0 eV) phases. Its response to UV light has led to increased interest in its application in the photocatalysis research field. It has been investigated extensively for its super hydrophilicity and use in environmental remediation and solar fuel production. In spite of extensive efforts to apply TiO2 for environmental remediation, photocatalytic activity in the visible region has remained quite low hence the ultimate goal of this research was to fabricate highly photoactive catalysts composed of non-metal, platinum-group metal (PGM) co-doped TiO2 and carbon nanotubes (CNTs) and to apply them for water purification using solar radiation...
Siame, John. "Study on selective precipitation of platinum and base metals in liquid-liquid and gas-liquid chloride systems : focus on conceptual process design." Thesis, 2012. http://encore.tut.ac.za/iii/cpro/DigitalItemViewPage.external?sp=1000297.
Повний текст джерелаThis study provides experimental data and new perspectives on selective precipitation of platinum group metals (PGMs) in the presence of base metals while at the same time reviewing the mass transfer characteristics and models associated with metal sulphides precipitation in liquid-liquid and gas-liquid systems. In this study, the objective was to investigate and validate the concept of selective precipitation of platinum from chloride media using sulphur-bearing liquids or gases.
Basu, Nivedita. "Exploration of Materials and Platforms for the Development of a Label-free Electrochemical DNA Sensor." Thesis, 2017. http://etd.iisc.ac.in/handle/2005/4309.
Повний текст джерелаMukri, Bhaskar Devu. "Synthesis, Structure and Catalytic Properties of Pd2+, Pt2+ and Pt4+ Ion Substituted TiO2." Thesis, 2013. http://etd.iisc.ac.in/handle/2005/3346.
Повний текст джерелаMukri, Bhaskar Devu. "Synthesis, Structure and Catalytic Properties of Pd2+, Pt2+ and Pt4+ Ion Substituted TiO2." Thesis, 2013. http://etd.iisc.ernet.in/2005/3346.
Повний текст джерелаSteyn, Marthinus Hendrik. "Pt and Au as electrocatalysts for various electrochemical reactions / Marthinus Hendrik Steyn." Thesis, 2015. http://hdl.handle.net/10394/15579.
Повний текст джерелаMSc (Chemistry), North-West University, Potchefstroom Campus, 2015
Συρροκώστας, Γιώργος. "Ανάπτυξη και μελέτη ημιαγώγιμων και μεταλλικών νανοδομών για εφαρμογή σε φ/β κυψελίδες και φωτοηλεκτροχρωμικές διατάξεις". Thesis, 2013. http://hdl.handle.net/10889/6434.
Повний текст джерелаIn this PhD thesis we have studied and prepared nanostructured titanium dioxide (TiO2) and platinum (Pt) thin films, in order to use them for dye sensitized solar cells. The morphology and the structure of the TiO2 films were examined with scanning electron microscopy (SEM) and x-ray diffraction (XRD). We have proposed the use of nitric acid, among four other acids, in order to achieve a more efficient dispersion of TiO2 nanoparticles and to prepare uniform and crack free films, with thickness above 10 μm. The TiO2 films were used in dye sensitized solar cells and was examined the relation between the structure of the films and the efficiency of the cells. For the deposition of Pt films we have used two different methods (thermal decomposition of Pt salts and electrodeposition). The films were characterized according to their morphology and their catalytic activity towards triiodide ions reduction. Moreover we have proposed methods for improving the properties of Pt films and we have studied their stability, especially when the films were stored in the same electrolyte solution as that in dye sensitized solar cells. Finally the TiO2 and Pt films were used in photoelectrochromic devices, where the energy produced by the photovoltaic cell is used for the modulation of device’s transmittance. Also a new type of a photoelectrochromic device was introduced and studied.
Huang, Wen-Jiun, and 黃文駿. "Nitrogen Doped Titanium Dioxide Films Deposited by Arc Ion Plating." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/28647156382502797300.
Повний текст джерела輔仁大學
物理學系
99
The purposes of this studyis to reduce the energy gap of TiO2 films by doping nitrogen, so that the films can still have phtocatalytic effect in visible light. This experiment consists of two parts. At the first part, we deposit TiO2 film by arc ion plating to understand its general characteristic. At the same time ,we observe the films surface structure by Electron Microscope(SEM) and Atomic Force Microscope(AFM) and find the best ellipsometry model to fit Optical constant. And then we use different nitrogen pressure to deposit the N-doped TiO2 films and fitting by the best ellipsometry model. Research the relationship between nitrogen pressure and optic characteristic. The results show that index of refraction and deposition rate increase as the flux of nitrogen increases, but index of refraction turn down when the nitrogen pressure is 4.4×10-3 torr. At the second part, we research the energy gap of film, phtocatalytic effect and binding . Because all the film in this research are amorphous, we use the ellipsometry TL-model fitting band gap. The results show that when the flux of nitrogen increases, the energy gap is gradually narrowing, but it will turn up when nitrogen pressure up to3.0x10-3torr. Besides, we proved the accordingly by photocatalyst Methylene Blue test, and when the above-mentioned happened, the N-doped TiO2 films binding had been changed. We can also evidence the change with XPS. In conclusion, we have been narrowed the original TiO2 film energy gap effectively, and confirmed the phtocatalytic effect through Methylene Blue test in this research.
Chiu, Te-Huang, and 邱德煌. "Dye-sensitized Titanium Dioxide Solar Cell Prepared by Arc Ion Plating." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/11691474771196409979.
Повний текст джерела逢甲大學
材料科學所
93
The great demand for petrochemical energy has led to the development of alternative power sources, such as solar cells, recent years and is expected to be clean energy source of the future. Development of solar cells from silicon-based devices to the new dye-sensitized type, referred to as dye-sensitized solar cells (DSSC), is a great step forward in this area, such as simpler fabrication techniques and reduced costs. The most common DSSC under current development is the titanium dioxide based type. Various production methods have been developed to fabricate TiO2 films for DSSC. The wet processes used are extensively investigated, but have disadvantages in terms of chemical by-products and the requirement for a post heat treatment, of over 400°C, in order to encourage anatase crystal growth. To overcome these short falls, vacuum deposition processes have been developed for the deposition of TiO2 layers. In this study, an arc ion plating (AIP) system shall be used to prepare the TiO2 layer, as this process is environmentally friendly, clean, relatively uncomplicated and may reduce solar cell production costs. Deposition parameters including oxygen partial pressure, substrate bias, deposition pressure and deposition time are varied to examine their effects on the microstructure and photovoltaic efficiency of the TiO2 deposits in form of the device ITO glass/〔TiO2(N3 dye)〕/ I + LiI electrolyte/Pt/ITO glass. Experimental results show that the increased oxygen partial pressure over 0.35 Pa favors the growth of stiochiometric TiO2 films, which are visually transparent and present anatase crystal structure. The substrate bias induces a denser film growth and hence higher transparency. When increasing deposition pressure, anatase phase become dominate and a loose film structure can be obtained due to thermalization effect. An excessive deposition pressure leads to the fine-grain growth of the deposit. In contrast to the thinner film deposited at shorter time, the thicker film presents less amount of rutile phase and high specific surface area. A dual-target AIP enhances the film growth rate. In summary the microstructure mentioned above, short current as an indication of photovoltaic efficiency of the solar cell device composed of AIP-TiO2 can be increased by the increasing oxygen partial pressure due to the increased amount of high crystallinity stiochiometric TiO2 film. A negative effect to the short current can be found by applying substrate bias owing to the reduced specific surface area of the denser film. The increased deposition pressure although is beneficial to the growth of loose films which exhibit higher short current, an excessive deposition pressure would then cause the fine-grain growth of the deposit and eventually decrease short current. A longer deposition time facilitate a thicker film with lager specific surface area there by larger short current. Under a pure oxygen deposition condition without substrate bias, a TiO2 film deposited for 60 min posses a short current of 0.052 mA/cm2 in corresponding to a photovoltaic efficiency of 0.08%. The dual-target AIP system minimizes the deposition time into 30 min while results similarly. Accordingly, the photovoltaic efficiency of AIP-TiO2 film is necessitated by the amount of anatase phase in the deposit. It is then determined by the specific surface area of the deposited film. It is recommended that an optimized TiO2 film can be obtained in a deposition condition with pure oxygen, under moderate deposition pressure whilst keeping no substrate bias for a satisfactory deposition time. Also noticeable is the substrate temperature can be below 350℃.
Su, Chih-Wei, and 蘇志偉. "A Study on the Preparation of Photocatalytic Titanium Dioxide Thin Film by Arc Ion Plating." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/cph2w9.
Повний текст джерела逢甲大學
材料科學所
91
Titanium dioxide photocatalyst is well developed and wildly used due to its safety, highly catalytic activity, and self-cleaning properties. However, recycling of TiO2 powder is difficult. This motivates the development of TiO2 thin-films processes to extend its application. In this study, arc ion plating technique was used to deposit TiO2 films on glass substrate. The influence of three most effective deposition parameters - deposition time, oxygen partial pressure, and substrate bias were discussed respectively. The cross sectional morphology, surface morphology, and microstructure was observed by SEM and XRD respectively. The photocatalysis-induced decolorization of methylene blue aqueous solution was measured by UV-visible spectrometer as an indication of photocatalytic activity of TiO2 thins to reveal the relationship between deposition parameters, film structure, and photocatalytic property. Experimental results show that the deposited films with anatase structure exhibit the higher photocatalytic efficiency. Photocatalytic efficiency increases with the fraction of anatase phase in TiO2 films. Crystallinity of TiO2 films is not only affected by substrate temperature but also by oxygen partial pressure. In high oxygen atmosphere, the probability of titanium ions reacting with oxygen to form the saturated TiO2 stoichiometry is increased, so that higher photocatalysis efficiency is obtained. Surface hardness of TiO2-coated glass specimen was found to be dependent on film thickness. The scratch test results show that the TiO2 films remain fully adherent. It is demonstrated that using arc ion plating can deposit photocatalytic TiO2 films onto glass substrate successfully. The high mechanical strength of films also promotes their potential in future environmental application.
CHANG, MING-KAI, and 張洺愷. "Study on the Effect of Plating Parameters and Saccharin Content over the Properties of Nickel Coating Electroplated by Using Supercritical Carbon Dioxide Mixed with Deep Eutectic Solvents." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/pu8xhp.
Повний текст джерела國立臺北科技大學
製造科技研究所
107
Deep eutectic solvent (DES) is a new generation of ionic liquids. It has the advantages of cheap raw materials, simple synthesis, non-toxic, biodegradable, non-flammable, non-volatile, high viscosity, easy to store and good solubility. DES has the potential to replace traditional aqueous solutions as a new generation of organic and inorganic solvents. Supercritical CO2 has low viscosity, low surface tension and high diffusivity. The coating prepared in supercritical CO2 environment has good coverage and uniformity. The supercritical CO2 process can increase the hardness of the coating when used in electroplating solution. In this study, DES from the mixture of choline chloride and urea in 1:2 molar ratio and supercritical carbon dioxide was used as the electrolyte for electroplating nickel. Our study has found that the Ni coating prepared in the DES has a higher hardness than conventional aqueous solutions. Moreover, with the introduction of supercritical carbon dioxide further increased the coating’s hardness than its conventionally electroplated counterpart. Due to the low surface tension properties of supercritical carbon dioxide, the electroplated Ni coating has better surface roughness than conventional plating. The raise in the DES electrolyte temperature increased the current efficiency in plating because of the higher ion transfer efficiency. Adding saccharin in supercritical plating can improve current efficiency, lower grain size, surface roughness, internal stress and raise corrosion resistance.
Gaidi, Mounir. "FILMS MINCES DE SNO2 (DIOXYDE D'ETAIN) DOPES AU PLATINE OU AU PALLADIUM ET UTILISES POUR LA DETECTION DES GAZ POLLUANTS : ANALYSES IN-SITU DES CORRELATIONS ENTRE LA REPONSE ELECTRIQUE ET LE COMPORTEMENT DES AGREGATS METALLIQUES." Phd thesis, 1999. http://tel.archives-ouvertes.fr/tel-00010787.
Повний текст джерела