A presente Tese, elaborada pela integração de artigos científicos publicados ou submetidos em periódicos internacionais, tem por objetivo geral investigar as potencialidades e limitações de resíduos industriais, acadêmicos e agroindustriais na obtenção de catalisadores para degradação de poluentes orgânicos. Foram utilizados resíduos industriais (banhos de galvanização, areias de fundição e petroquímico), acadêmicos (soluções residuais de aula de fotografia contendo prata e solução residual das aulas de química analítica contendo metais) e agro-industriais (casca de arroz, casca de acácia esgotada, pó de fumo) na preparação dos fotocatalisadores suportados. Os sólidos foram caracterizados por um conjunto de técnicas espectroscópicas, volumétricas, microscópicas, eletroquímicas visando descrever os catalisadores do ponto de vista, elementar, estrutural, textural e morfológico, como espectroscopia de emissão de raios X por dispersão de energia (SEM-EDX), espectroscopia de retroespalhamento Rutherford (RBS), espectroscopia de reflectância difusa no ultravioleta (DRS-UV), espectroscopia de espalhamento de raios X em baixo ângulo (SAXS), espectroscopia de fotoelétrons excitados por raios X (XPS), porosimetria de nitrogênio e medidas de potencial zeta (ZP). Os sistemas foram avaliados na fotodegradação de corante (rodamina B), fenol e fármacos sob radiação ultravioleta e visível. Para fins de comparação, titânia comercial P25 (Degussa) foi empregada como catalisador. Além disso, o efeito da reutilização dos catalisadores e atividade fotocatalitica frente a amostras reais foram estudados. O catalisador suportado preparado a partir do resíduo da indústria petroquímica e suportado em sílica apresentou a melhor atividade fotocatalítica na degradação de todas as moléculas testadas, tal como RhB (67 % sob radiação UV e 61 % sob radiação visível), fármaco guaifenesin ( 49 % UV e 45 % visível) e fenol (44 % UV), enquanto que o P25 comercial apresentou 93 % e 14 %, respectivamente, para a radiação ultravioleta e visível. / This thesis, developed by the integration of scientific papers published or submitted in international journals, has the objective to investigate the potential and limitations of industrial waste, academics and agroindustrial to obtain catalysts for degradation of organic pollutants. Industrial waste (galvanic baths, foundry sands and petrochemical), academics (residual solutions of class photograph containing silver and residual solution of analytical chemistry classes containing metals) and agroindustrial (rice husk, exhausted bark acacia, tobacco dust) were used in the preparation of the supported photocatalyst. The solids were characterized by a set of spectroscopic, volumetric, microscopic electrochemical techniques in order to describe elementary structural, textural and morphological properties, such as Scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX), Rutherford backscattering spectrometry (RBS), diffuse reflectance spectroscopy in the ultraviolet (DRS-UV), small-angle X-ray scattering (SAXS), X-ray Photoelectron Spectroscopy (XPS), nitrogen porosimetry and zeta potential (ZP) measurements. The catalyst activity was evaluated on the dye (RhB), phenol and drugs photodegradation under ultraviolet and visible radiation. For comparative reasons, P25 (Degussa) was also employed as the catalyst. Furthermore, the effect of reuse of catalysts and photocatalytic activity compared to real samples were also evaluated. The silica supported catalyst prepared from petrochemical waste and supported on silica showed the best photocatalytic activity in the degradation of all tested molecules, such as RhB (67% and 61% under UV and visible radiation, respectively), guaifenesin drug (49% UV and 45 % visible radiation) and phenol (44 % UV radiation), while the commercial P25 showed 93 % and 14 %, to ultraviolet and visible radiation, respectively.

abstract: Photocatalytic water splitting has been proposed as a promising way of generating carbon-neutral fuels from sunlight and water. In one approach, water decomposition is enabled by the use of functionalized nano-particulate photocatalyst composites. The atomic structures of the photocatalysts dictate their electronic and photonic structures, which are controlled by synthesis methods and may alter under reaction conditions. Characterizing these structures, especially the ones associated with photocatalysts’ surfaces, is essential because they determine the efficiencies of various reaction steps involved in photocatalytic water splitting. Due to its superior spatial resolution, (scanning) transmission electron microscopy (STEM/TEM), which includes various imaging and spectroscopic techniques, is a suitable tool for probing materials’ local atomic, electronic and optical structures. In this work, techniques specific for the study of photocatalysts are developed using model systems. Nano-level structure-reactivity relationships as well as deactivation mechanisms of Ni core-NiO shell co-catalysts loaded on Ta2O5 particles are studied using an aberration-corrected TEM. It is revealed that nanometer changes in the shell thickness lead to significant changes in the H2 production. Also, deactivation of this system is found to be related to a photo-driven process resulting in the loss of the Ni core. In addition, a special form of monochromated electron energy-loss spectroscopy (EELS), the so-called aloof beam EELS, is used to probe surface electronic states as well as light-particle interactions from model oxide nanoparticles. Surface states associated with hydrate species are analyzed using spectral simulations based on a dielectric theory and a density of states model. Geometry-induced optical-frequency resonant modes are excited using fast electrons in catalytically relevant oxides. Combing the spectral features detected in experiments with classical electrodynamics simulations, the underlying physics involved in this excitation process and the various influencing factors of the modes are investigated. Finally, an in situ light illumination system is developed for an aberration-corrected environmental TEM to enable direct observation of atomic structural transformations of model photocatalysts while they are exposed to near reaction conditions. / Dissertation/Thesis / Doctoral Dissertation Materials Science and Engineering 2018

Made available in DSpace on 2015-05-14T13:21:40Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 3260499 bytes, checksum: 5bc01451ca6efdedd221c478c2647b55 (MD5) Previous issue date: 2014-08-01 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The need to control textile effluents due to contamination of rivers has led CONAMA to regulate and require a more efficient treatment process. Among the methods of treatment, heterogeneous catalysis stands out due to its high efficiency. The most used photocatalyst is TiO2. The combination of this material with other ones has been employed to improve its activity and/or its performance. Several systems have been tested, including the core-shell that constitutes a complete coverage of one material by another. In this work, TiO2@CoFe2O4 was synthesized by the modified-Pechini method with the addition of CoFe2O4 nanoparticles into the polymeric resin containing titanium. A magnetic material was obtained, which was characterized by X-ray diffraction (XRD), infrared spectroscopy (IR), ultraviolet - visible spectroscopy (UV-Vis), specific surface area by the BET method. The materials were applied in the photodiscoloration of an azo dye. The pure TiO2 calcined at 700 °C showed a mixture of phases anatase / rutile in the proportions 77/23%, which was the calcination temperature which led to the highest photocatalytic activity in the discoloration of the solution yellow gold remazol (RNL). A discoloration of 81% in color of the solution was attained after 6 h of exposure to UV light, while 94% was reached after 2 h of irradiation with sunlight. With the core@shell system CoFe2O4@TiO2 synthesized with 90 % of TiO2, a mixture of anatase and rutile of 92 : 8% was obtained for a calcination temperature of 500 °C. This material showed 76% discoloration after 16 h of exposure to UV light under the same conditions used for the test with pure TiO2 / A necessidade do controle de efluentes têxteis devido à contaminação de águas fluviais tem levado órgãos como o CONAMA a regulamentar e exigir um processo de tratamento mais eficiente. Dentre os métodos de tratamento estudados, os Processos Oxidativos Avançados (POA) têm demonstrado grande eficiência, como na fotocatálise heterogênea utilizando materiais semicondutores, sendo o TiO2 um dos mais empregados. A combinação deste material com outros tem sido estudada com o objetivo de melhorar a atividade e/ou performance do mesmo. Para isso vários sistemas têm sido utilizados, dentre eles o core@shell, que consiste na completa cobertura de um material por outro. Neste trabalho o CoFe2O4@TiO2 foi sintetizado pelo método Pechini modificado, com a adição do CoFe2O4 nanoparticulado à uma resina polimérica de titânio, sendo obtido um material magnético, o qual foi caracterizado por difração de raios X (DRX), espectroscopia infravermelho (IV), espectroscopia na região ultravioleta e visível (UV-Vis), análise de área superficial específica pelo método de BET. Os materiais foram testados na fotodegradação de um corante azo. O TiO2 puro calcinado a 700 ºC, apresentou mistura de fases anatase / rutilo com proporção 77 / 23 %, sendo a temperatura de calcinação que levou à maior atividade fotocatalítica na descoloração da solução de amarelo ouro remazol (RNL). Foi obtida 81 % de redução da cor da solução em 6 h de exposição a luz UV e 94 % após 2 h com irradiação de luz solar. Com o sistema core@shell CoFe2O4@TiO2 sintetizado com 90 % de TiO2 foi obtida uma mistura de 92 % de anatase e 8 % de rutilo, para uma temperatura de calcinação de 500 ºC. Este material levou a 76 % de descoloração em 16 h de exposição à luz UV com as mesmas condições utilizadas para o teste com o TiO2 puro

A presente Tese, elaborada pela integração de artigos científicos publicados ou submetidos em periódicos internacionais, tem por objetivo geral investigar as potencialidades e limitações de resíduos industriais, acadêmicos e agroindustriais na obtenção de catalisadores para degradação de poluentes orgânicos. Foram utilizados resíduos industriais (banhos de galvanização, areias de fundição e petroquímico), acadêmicos (soluções residuais de aula de fotografia contendo prata e solução residual das aulas de química analítica contendo metais) e agro-industriais (casca de arroz, casca de acácia esgotada, pó de fumo) na preparação dos fotocatalisadores suportados. Os sólidos foram caracterizados por um conjunto de técnicas espectroscópicas, volumétricas, microscópicas, eletroquímicas visando descrever os catalisadores do ponto de vista, elementar, estrutural, textural e morfológico, como espectroscopia de emissão de raios X por dispersão de energia (SEM-EDX), espectroscopia de retroespalhamento Rutherford (RBS), espectroscopia de reflectância difusa no ultravioleta (DRS-UV), espectroscopia de espalhamento de raios X em baixo ângulo (SAXS), espectroscopia de fotoelétrons excitados por raios X (XPS), porosimetria de nitrogênio e medidas de potencial zeta (ZP). Os sistemas foram avaliados na fotodegradação de corante (rodamina B), fenol e fármacos sob radiação ultravioleta e visível. Para fins de comparação, titânia comercial P25 (Degussa) foi empregada como catalisador. Além disso, o efeito da reutilização dos catalisadores e atividade fotocatalitica frente a amostras reais foram estudados. O catalisador suportado preparado a partir do resíduo da indústria petroquímica e suportado em sílica apresentou a melhor atividade fotocatalítica na degradação de todas as moléculas testadas, tal como RhB (67 % sob radiação UV e 61 % sob radiação visível), fármaco guaifenesin ( 49 % UV e 45 % visível) e fenol (44 % UV), enquanto que o P25 comercial apresentou 93 % e 14 %, respectivamente, para a radiação ultravioleta e visível. / This thesis, developed by the integration of scientific papers published or submitted in international journals, has the objective to investigate the potential and limitations of industrial waste, academics and agroindustrial to obtain catalysts for degradation of organic pollutants. Industrial waste (galvanic baths, foundry sands and petrochemical), academics (residual solutions of class photograph containing silver and residual solution of analytical chemistry classes containing metals) and agroindustrial (rice husk, exhausted bark acacia, tobacco dust) were used in the preparation of the supported photocatalyst. The solids were characterized by a set of spectroscopic, volumetric, microscopic electrochemical techniques in order to describe elementary structural, textural and morphological properties, such as Scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX), Rutherford backscattering spectrometry (RBS), diffuse reflectance spectroscopy in the ultraviolet (DRS-UV), small-angle X-ray scattering (SAXS), X-ray Photoelectron Spectroscopy (XPS), nitrogen porosimetry and zeta potential (ZP) measurements. The catalyst activity was evaluated on the dye (RhB), phenol and drugs photodegradation under ultraviolet and visible radiation. For comparative reasons, P25 (Degussa) was also employed as the catalyst. Furthermore, the effect of reuse of catalysts and photocatalytic activity compared to real samples were also evaluated. The silica supported catalyst prepared from petrochemical waste and supported on silica showed the best photocatalytic activity in the degradation of all tested molecules, such as RhB (67% and 61% under UV and visible radiation, respectively), guaifenesin drug (49% UV and 45 % visible radiation) and phenol (44 % UV radiation), while the commercial P25 showed 93 % and 14 %, to ultraviolet and visible radiation, respectively.

É urgente o desenvolvimento de novas tecnologias para o tratamento de água nos dias atuais. Neste contexto, os processos oxidativos avançados (POA) tem sido bem-sucedido no tratamento de contaminantes presentes em efluentes industriais e na rede de esgoto doméstico. Neste trabalho, estudamos um dos POA, a fotocatáliseheterogênea por meio da síntese de fotocatalisadores mistos de nióbio e titânio utilizando-se o método Pechini, com uma temperatura de calcinação de 470 oC. Foram sintetizados os fotocatalisadores PNB000, PNB018, PNB030, PNB070, PNB099 e PNB100, onde os números mostram aporcentagem em mols de pentóxido de nióbio presente em cada um deles. Estes fotocatalisadores foram submetidos a um segundo tratamento térmico a 800oC, durante 6 horas, e obtivemoso PNB000_01, PNB018_01, PNB030_01, PNB070_01 e PNB100_01. A caracterização dos fotocatalisadores foi feita por: análise de espectroscopia de energia dispersiva (EDS); área superficial determinadas por isotermas de adsorção e dessorção de nitrogênio, BET; imagens de microscopiaeletrônica de varredura (MEV); difração de raios-X; análises térmicas (termogravimetria e análise térmica diferencial), determinação de band gap por reflectância difusa. O potencial para serem usados como fotocatalisadores heterogêneos para degradação de compostos orgânicos foi avaliado pela eficiência fotônica de geração de radicais hidroxilas(OH)sob radiação de lâmpada UVA (15 W). A análise de EDS confirmou acomposiçãoem mol de TiO2 e Nb2O5presentes nosfotocatalisadoressintetizados. A área superficial obtida por isotermas (BET) do PNB018 (161,7 m²/g), PNB030 (130,8 m²/g), PNB070 (150,5 m²/g) mostraram-se maiores do que ado TiO2 P25 (52,68 m²/g). As imagens de MEV mostrou que estes fotocatalisadoressão constituídos de partículas manométricas. Outra característica dos óxidos com quantidade intermediária de mols de Nb2O5 (18, 30 e 70%) foi a estrutura amorfa determinada por difração de raios-X. Por sua vez, os óxidos tratados a 800oC apresentaram estruturas cristalinas edifratogramas de raios-X completamente diferentes do TiO2 e do Nb2O5, comprovando-se que são novos materiais.As medidas de energia de band gapmostrou diferenças significativas quando comparamos o TiO2 P25 (Egap 3,22eV) e o PNB000 (Egap 2,90eV). Isso leva a concluir que estes fotocatalisadores sintetizados pelo método Pechini necessitam de uma energia menor para que ocorram as transições eletrônicas. O fotocatalisador PNB070, que apresenta 70% em mols de pentóxido de nióbio, apresentouOH de 0,104 da mesma ordem de grandeza do TiO2 P25 (OH 0,134) e ligeiramente menor do que o OH do Nb2O5.nH2O (OH 0,164). Dessa maneira, supõe-se que o PNB070 tenha o mesmo potencial de eficiência que o TiO2 P25 para fotodegradações. Por sua vez, os fotocatalisadores que passaram por um segundo tratamento térmico a 800 oC mostraram valores de rendimento quântico de produção de radicais hidroxilas bem inferiores aos seus originais. Por exemplo, o PNB070_01 teve OH de 0,003. Esses resultados sugerem que o aumento da cristalinidade pode diminuir a atividade fotocatalítica, ou, que o estado amorfo dos fotocatalisadores deste trabalho favorece o aumento da velocidade de transferência de elétrons e a da fotocatálise. / Nowadays, the development of new technologies for the treatment of water is urgent. In this context, the advanced oxidative processes (AOP) has been successful in the treatment of contaminants foundin industrial effluents and domestic sewage. In this work, we have studied an AOP, the heterogenousphotocatalysis, by means the synthesis of niobium and titanium mixedphotocatalysts, employing calcination temperature of 470 oC.The PNB000, PNB018, PNB030, PNB070, PNB099 and PNB100photocatalysts were synthetized, where the numbers show the percentage in mol of Nb2O5content in each of them. These photocatalytswere submitted to a second heat treatment to 800oC during 6 hours, and PNB000_01, PNB018_01, PNB030_01, PNB070_01 and PNB100_01 were obtained. The characterization of the photocatalysts was made by: analysis of the energy dispersive spectroscopy (EDS); the surface area determined by adsorption and desorption isotherms of nitrogen, BET; images of scanning electron microscopy (SEM); X-ray diffraction; thermal analysis (thermogravimetry and differential thermal analysis), determination of the band gap by diffuse reflectance.Their potential to be used as heterogeneous photocatalystsfor degradation of organic compounds was evaluated by means the determination of the photonic efficiency for hydroxyl radical production (OH)under radiation of UV-A lamp (15 W). The EDS analysis confirmed the composition in mol of TiO2 and Nb2O5 present in the synthesizedphotocatalysts. Surface area obtained by isotherms (BET) of PNB018 (161.7 m ²/g), PNB030 (130.8 m ²/g), PNB070 (150.5 m ²/g) were higher than TiO2 P25 (52.68 m ²/g). SEM images showed that these photocatalysts consist of nanoparticles. Another feature of the oxides with intermediate amount of moles of Nb2O5 (18, 30 and 70%) was the amorphous structure determined by X-ray diffraction. On the other hand, the oxides treated to 800 oC showed crystalline structures and X-ray patternscompletely different from TiO2 and Nb2O5, proving that the synthetized oxides are new materials.The band gap energy measurements showed significant differences when we compare TiO2 P25 (Egap 3.22 eV) and the PNB000 (Egap 2.90 eV). This allow us to conclude that thephotocatalysts synthesized by Pechini method require lower energy in order to have electronic transitions. The PNB070 photocatalyst, which has 70% in mols of niobium pentoxide, showed OHof 0.104 of the same order of magnitude of TiO2 P25 (OH0.134) and slightly smaller than the OH of Nb2O5.nH2O (OH 0.164). For this reason, we can assume that PNB070 has the same potential of the TiO2 P25 for organic compound photodegradation. The photocatalyststhat were submittedthrough a second heat treatment at 800 oC showed quantum efficiency of hydroxyl radical production values well below their original. For instance, PNB070_01 showed OHof 0.003. These results suggest that increased crystallinity can reduce the photocatalytic activity, or the amorphous structures of the photocatalysts of this work improve the electron transfer rates and the photocatalysis.

Made available in DSpace on 2017-07-10T18:01:54Z (GMT). No. of bitstreams: 1 Andreia Peiter.pdf: 1366062 bytes, checksum: e0b82884da5c768cb61affcb50cffecf (MD5) Previous issue date: 2015-07-27 / According on the demand for processes that minimize the environmental impact generated by waste, efficient systems that make possible the degradation of these compounds and allow its use as an alternative source for renewable energy generation are increasingly required. The increasing food production to meet the needs of the world population has encouraged the use of agrochemicals in order to ensure productivity in crops. The use of insecticides is increasing to control pests and herbicides for weed control, because there is a lack of effective control that includes new production strategies. Techniques such as crop rotation, no-till system introduction and use of green pesticides (natural insecticides) provide a more sustainable agriculture and reduce impacts to the environment. In this context, this work presents an alternative development of an integrated system for remediation of environments contaminated with simultaneous generation of electricity. The materials were prepared from reagents and accessible metals, which reduce costs and contribute to a clean process, without the addition of organic additives. Due to the high oxidizing potential of hydroxyl radicals generated by the pair electron-hole (e+ + h+) in the semiconductors, was possible to degrade the organic compounds used in the system. The results showed that the generation of current in an area of 6,9 cm2 was 193,37 uA in potassium hydrogen phthalate degradation, using Cu/CuO electrode as a photocatalyst. The Aminol® and Connect® pesticides have been degraded at a percentage of 54,46% and 21,02%, respectively, after 1 hour and 30 minutes in the system, under ultraviolet radiation. The degradation of organic contaminants and simultaneous power generation of energy in integrated system provides a self-sustaining form of wastewater treatment and energy recovery, being possible its use on a large scale. / Em função da demanda por processos que minimizem os impactos ambientais gerados por resíduos, sistemas eficientes que possibilitem a degradação desses compostos e permitam sua utilização como fonte alternativa para geração de energia renovável são cada vez mais requeridos. A crescente produção de alimentos para suprir as necessidades da população mundial tem incentivado o emprego de agroquímicos com o objetivo de assegurar a produtividade nas lavouras. Cada vez mais aumenta o uso de inseticidas para o controle de pragas e herbicidas para o controle de ervas daninhas, pois há carência de um controle efetivo que inclua novas estratégias de produção. Técnicas como rotação de cultura, introdução do sistema de plantio direto e utilização de inseticidas verdes (inseticidas naturais) propiciam uma agricultura mais sustentável e reduzem os impactos causados ao ambiente. Nesse contexto, o presente trabalho apresenta uma alternativa de desenvolvimento de um sistema integrado para remediação de ambientes contaminados com geração simultânea de energia elétrica. Os materiais foram preparados a partir de reagentes e metais acessíveis, os quais reduzem os custos e contribuem para um processo mais limpo, sem a ação de aditivos orgânicos. Devido ao alto potencial oxidante dos radicais hidroxila gerados por meio do par elétron-lacuna (e- + h+) em semicondutores, foi possível degradar os compostos orgânicos utilizados no sistema. Os resultados mostraram que a geração de corrente em uma área de 6,9 cm2 foi de 193,37 µA na degradação do padrão hidrogenoftalato de potássio, utilizando eletrodo de Cu/CuO como fotocatalisador. Os agrotóxicos Aminol 806® e Connect® foram degradados com percentual de 54,46% e 21,02%, respectivamente, após 1 hora e 30 minutos no sistema, sob radiação ultravioleta. A degradação de contaminantes orgânicos e simultânea geração de energia no sistema integrado prevê uma forma autossustentável de tratamento de efluentes e recuperação de energia, sendo possível sua utilização em grande escala.

Solar energy is a sustainable resource which has substantial potential to meet the increasing demand for renewable energy. Though there has been some success in harvesting solar energy for electricity production, converting solar energy to chemical energy as fuels is still a challenge due to low efficiency. Since the discovery of TiO2 photocatalysts for splitting water (4) and reducing CO2 (5) to form useful chemical feedstock such as H2, CO and CH4, much research has been done to increase the efficiency of photocatalysts. However, the current conversion efficiency of photocatalysts remains low (~5%) (6, 7). Issues being addressed include the wide bandgap and mismatched band edge for reactions (thermodynamic energy for reaction), poor quantum efficiency of the photon collector systems, high recombination of e-/h+ pairs and limitation in the rate of charge transfer from photocatalyst to reactants. This work focuses on improving efficiency of photocatalysts for fuel production through several approaches: (1) engineering a metal-organic-framework (MOF) to have proper band gaps and band edges for targeted reactions and for enhancing photoadsorption in the visible light range, (2) tuning an ABO3-type perovskite for desired bandgaps and thermodynamically favored bandedges for CO2 reduction with water in visible light range. A porphyrin-based Ti-MOF is studied for CO2 photoreduction to gaseous chemical fuels such as CH4 and CO. The porphyrin linkers allow porphyrin-based MOF-525 to achieve narrow bandgap (Eg = ~1.7eV) to absorb visible light, indicating its ability to harvest more solar energy than conventional TiO2. Ti/Zr-MOF-525 also exhibited the appropriate energy level alignment for CO2 and H2O redox reaction for CO and CH4 production. Its CO2 photoreactivity under visible light was demonstrated in a photoreaction, illuminated by 150W Xenon solar simulator. Interestingly, Ti/Zr-MOF-525 demonstrates a selectivity toward CH4, a more valuable fuels than CO. The gas phase reaction condition is an advance over liquid photoreaction. The catalyst stability was also studied and presented. After 3 cycles of reactions, Ti/Zr-MOF-525 is relatively stable for CO2 photoreduction and able to maintain its photoreactivity at about 60-65% of fresh catalyst. The reduction of reactivity is due to a less stable fresh catalyst. When investigating LaCr1-xFexO3 perovskite oxides for photocatalyst, it was found that when replacing Cr ions at the B sites of LaCrO3 by Fe ions, the bandgap does not follow a linear trend in regards to metal ratio composition but rather reflects the smaller bandgap of LaFeO3. Bandedges were successfully measured for the new synthesized materials. At x = 0.25, the conduction band potential remains similar with x = 0. However, at x = 0.75, the conduction band potential was more negative than either perovskites at x = 0 or x = 1. Future simulation of density of state could address this interesting observation. CO2 reduction relativities of each perovskites were predicted well by their measured bandgaps and bandedges. Among five studied perovskites, synthesized LaCr0.25Fe0.75O3 (x = 0.75) is the most active for CO2 photoreduction under visible illumination at room temperature thanks to its small bandgap (2.0 eV) and its suitable bandedges for CO2 photoreduction.

京都大学 / 0048 / 新制・課程博士 / 博士(人間・環境学) / 甲第22550号 / 人博第953号 / 新制||人||226(附属図書館) / 2019||人博||953(吉田南総合図書館) / 京都大学大学院人間・環境学研究科相関環境学専攻 / (主査)教授 吉田 寿雄, 教授 内本 喜晴, 教授 田部 勢津久 / 学位規則第4条第1項該当 / Doctor of Human and Environmental Studies / Kyoto University / DFAM

京都大学 / 新制・課程博士 / 博士(エネルギー科学) / 甲第23536号 / エネ博第427号 / 新制||エネ||81(附属図書館) / 京都大学大学院エネルギー科学研究科エネルギー社会・環境科学専攻 / (主査)教授 石原 慶一, 教授 佐川 尚, 准教授 奥村 英之 / 学位規則第4条第1項該当 / Doctor of Energy Science / Kyoto University / DFAM

京都大学 / 新制・課程博士 / 博士(工学) / 甲第23216号 / 工博第4860号 / 新制||工||1759(附属図書館) / 京都大学大学院工学研究科物質エネルギー化学専攻 / (主査)教授 阿部 竜, 教授 陰山 洋, 教授 藤田 晃司 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM