Nanocatalysis has emerged in the last decades as an interface between homogeneous and heterogeneous catalysis, offering simple solutions to problems that conventional materials have not been able to solve. In fact, nanocatalyst design permits to obtain structures with high superficial area, reactivity and stability, and at the same time presenting good selectivity and facility of separation from reaction mixtures. In this work, we prepared hybrid structures comprising gold, palladium and silver nanoparticles (Au, Pd and Ag NPs), titanate nanosheets (TixO2), graphene oxide (GO), and partially reduced graphene oxide (prGO). We focused on bi- and tri-components hybrids, namely TixO2, M/(pr)GO and M/TixO2/(pr)GO (M = Au, Pd or Ag) and developed facile, versatile and environment-friendly preparation methods with an emphasis on control over physicochemical features such as size, shape and composition. In order to exploit the catalytic applications, we employed the reduction of 4-nitrophenol as a model reaction, followed by visible-light assisted oxidation of p-aminothiophenol (PATP). With these tests, we unraveled metal-support interactions and cooperative effects that render hybrid structures superior to their individual counterparts. / A nanocatálise surgiu nas últimas décadas como uma interface entre catálise homogênea e heterogênea, oferecendo soluções simples a problemas que os materiais convencionais não conseguiram resolver. De fato, o design de nanocatalisadores permite obter estruturas com grande área superficial, reatividade e estabilidade, e ao mesmo tempo apresentando boa seletividade e facilidade de separação de misturas reacionais. Neste trabalho apresentamos a preparação de estruturas híbridas compostas por nanopartículas de ouro, paládio e prata (Au, Pd e Ag NPs), nanofolhas de titanato (TixO2), óxido de grafeno (GO) e óxido de grafeno parcialmente reduzido (prGO). Focamos em híbridos do tipo M/TixO2, M/(pr)GO e M/TixO2/(pr)GO (M = Au, Pd ou Ag) e desenvolvemos métodos de preparação simples, versáteis e ambientalmente amigáveis, com ênfase no controle sobre tamanho, forma e composição. Para explorar as potencialidades catalíticas utilizamos a redução do 4-nitrofenol como reação modelo, e em seguida a oxidação assistida por luz do p-aminotiofenol (PATP). Com esses testes, investigamos interações metal-suporte e efeitos cooperativos que tornam as estruturas hibridas superiores a cada um dos materiais que as compõem.

Este trabalho descreve a síntese e caracterização de polímeros de coordenação (PC) e sua aplicação como fotocatalisadores heterogêneos ativos sob a radiação visível, visando a degradação de compostos orgânicos em água. Problemas ambientais têm ocupado posição de destaque na sociedade contemporânea. Dentre eles, o uso de combustíveis fósseis e a remoção de compostos poluentes do meio ambiente têm merecido especial atenção. Uma das alternativas mais indicadas como substituinte dos combustíveis fósseis é a energia solar, por ser limpa, renovável e presente em todo o planeta. O estudo de materiais fotoativos é essencial para aproveitar ao máximo essa fonte. A fotocatálise é um processo que utiliza a energia luminosa para realizar reações químicas. Os PC têm mostrado ótimos resultados na área. Esses são compostos poliméricos cujos monômeros são unidades de coordenação. Neste trabalho foram sintetizados PC formados por diferentes metais de transição e ligantes orgânicos. Dentre eles destacam-se níquel e benzenodicarboxilato (Ni-BDC). Os materiais foram caracterizados por FTIR, DRX, adsorção-dessorção de N2, DRS, TGA, MEV e ICP-OES. Os resultados sugerem a formação de PC inéditos, dotados de sítios de coordenação insaturados, com boa estabilidade térmica, porém com estabilidade em meio aquoso inferior. O ensaio de degradação fotocatalítica de corante evidencia que os materiais são fotoativos na luz visível, apesar da descoloração não ser completa. Este resultado é interessante, pois polímeros de coordenação de níquel ainda são pouco estudados como fotocatalisadores, e esse é um metal barato e abundante. / This work describes the synthesis and characterization of coordination polymers (CP) and their application as heterogeneous photocatalysts, under visible radiation, in degradation of organic compounds in water. Environmental issues have taken prominent position in contemporary society. Among them, fossil fuel usage and removal of hazardous compounds deserve special attention. One of the best alternatives to replace fossil fuels is the solar power, which is clean, renewable and ubiquitous throughout the planet. Research on photoactive materials is essential to improve this energy source use. Heterogeneous photocatalysis process uses light energy to induce chemical reactions. CP are exhibiting remarkable results in the field. These are polymeric compounds with coordination units as monomers. In the present work, CP based on different transition metals and organic ligands were synthesized, such as nickel benzenedicarboxylate (Ni-BDC). The materials were characterized by FTIR, XRD, N2 adsorption-desorption, DRS, TGA, SEM and ICPOES. The results suggest the formation of novel CP, endowed with unsaturated metal sites and good thermal stability, however with low stability in aqueous medium. The photocatalytic dye degradation experiments indicate the materials are photoactive under visible light, although the discoloration was not complete. This is an interesting result, considering that the research on nickel coordination polymers as photocatalysts is still scarce.

A aplicação de semicondutores no tratamento de água e efluentes líquidos é uma tecnologia de remediação ambiental promissora, em especial para poluentes orgânicos. Entre os vários semicondutores que também são fotocatalisadores, o TiO2 é amplamente usado em aplicações ambientais, por ser inerte biológica e quimicamente, ter elevado potencial de oxidação, baixo custo e estabilidade frente à corrosão. Entretanto, o TiO2 também tem algumas desvantagens, tais como: ele é excitado apenas por luz UV e requer uma operação unitária adicional (por exemplo, filtração ou centrifugação) para o reuso do catalisador. Para contornar estas limitações, usou-se um procedimento simples para a síntese de um fotocatalisador magnético (Fe3O4/TiO2) com alta área superficial específica e atividade catalítica, quando comparado com o TiO2 P25 da Evonik. O fotocatalisador foi sintetizado através de um procedimento em três etapas: (1) Partículas α-Fe2O3 foram obtidas por precipitação de uma solução de FeCl3.6H2O 0.01 mol L-1, que foi submetida a uma hidrólise forçada à 100°C por 48 h; (2) Partículas de α-Fe2O3/TiO2 foram obtidas por heterocoagulação de oxi-hidróxidos de Ti(IV) sobre as partículas de α-Fe2O3, as quais foram calcinada a 500°C por 2 h; e (3) As partículas \"casaca/caroço\" do fotocatalisador foram obtidas por calcinação a 400°C por 1 h sob atmosfera redutora (H2). A atividade fotocatalítica do material sintetizado foi avaliada aplicando-o no descoramento de uma solução do corante Azul Ácido 9 (C.I. 42090). Os efeitos do pH e da concentração de catalisador foram estimados por meio de um planejamento fatorial 22. Foi obtido um fotocatalisador com área superficial específica de 202 m2 g-1, facilmente separável do meio reacional em aproximadamente 2 min com o auxílio de um ímã. O fotocatalisador apresentou absorção em toda a região do visível. A maior remoção de cor (54%) foi obtida com pH 3,0, 1,0 g L-1 de catalisador e 2 horas de reação. / The use of semiconductors for treating polluted waters and wastewaters is a promising environmental remediation technology, especially for organic pollutants. Among the several semiconductors that are also photocatalysts, TiO2 is extensively used for environmental application, due to its biological and chemical inertness, high oxidation power, low cost, and stability regarding corrosion. However, TiO2 also has some disadvantages, such as: it is only UV-excited and requires an additional unit operation (e.g. filtration or centrifugation) for reuse purposes. In order to work around those limitations, a simple procedure for synthesizing a magnetic photocatalyst (Fe3O4/TiO2), with high specific surface area and good photocatalytic activity when compared to Evonik\'s TiO2 P25, was used. The photocatalyst was synthesized in a three-step procedure: (1) α-Fe2O3 particles were obtained, by precipitation, from FeCl3.6H2O 0.01 mol L-1, which underwent a forced acid hydrolysis at 100°C for 48 h; (2) α-Fe2O3/TiO2 particles were obtained, by heterocoagulation, of Ti(IV) oxide species on the α-Fe2O3, followed by calcination at 500°C for 2 h; and (3) The core/shell photocatalyst particles were obtained by calcination the α-Fe2O3/TiO2 particles at 400°C for 1 h under reducing atmosphere (H2). The photocatalytic activity of the synthesized material was assessed by the color removal of an Acid Blue 9 (C.I. 42090) dye solution. pH and catalyst dosage effects were estimated by a 22 factorial design. Fe3O4/TiO2 core/shell particles with specific surface area of 202 m2 g-1were obtained. They were easily separated from the reaction medium, in approximately 2 min, with the aid of a magnet. The photocatalyst absorbed radiation throughout the visible spectrum. The greatest color removal (54%) was achieved with pH 3.0, 1.0 g L-1 of photocatalyst, and 2 h of reaction.

Chen, Yanmin. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references (leaves 140-160). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

by Yuk-Lin Chan. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1999. / Includes bibliographical references (leaves 78-83). / Abstracts in English and Chinese. / Abstract (English version) --- p.i / Abstract (Chinese version) --- p.ii / Acknowledgments --- p.iii / Table of Contents --- p.iv / List of Figures --- p.vi / List of Tables --- p.vii / Chapter 1. --- Introduction / Chapter 1.1 --- Indoor Air Pollution --- p.1 / Chapter 1.2 --- Typical Treatment of Air Pollutant --- p.6 / Chapter 1.3 --- Photocatalytic Degradation over Titanium Dioxide --- p.7 / Chapter 1.4 --- Advantages of Titanium Dioxide as a Photocatalyst --- p.12 / Chapter 1.5 --- Applications of Photocatalytic Degradation in Pollution Control --- p.14 / Chapter 1.5.1 --- Aqueous Phase Decontamination --- p.15 / Chapter 1.5.2 --- Gas Phase Decontamination --- p.15 / Chapter 1.6 --- Development of the Photocatalytic Degradation Technique --- p.16 / Chapter 1.6.1 --- Pure Ti02 --- p.17 / Chapter 1.6.2 --- Design of the Reactors --- p.18 / Chapter 1.6.3 --- Metal Ion Dopants --- p.21 / Chapter 1.6.4 --- Mixture with Supports --- p.21 / Chapter 1.7 --- Adsorbent-Supported Titanium Dioxide --- p.22 / Chapter 1.7.1 --- Use of Adsorbents other than Zeolites --- p.22 / Chapter 1.7.2 --- Use of Zeolites --- p.25 / Chapter 1.8 --- Molecular Sieves --- p.29 / Chapter 2. --- Experimental / Chapter 2.1 --- Block diagram of the Reaction Setup --- p.31 / Chapter 2.2 --- Fixed Volume Batch Reactor --- p.32 / Chapter 2.3 --- Reagents --- p.34 / Chapter 2.3.1 --- Degussa P25 Ti02 powder --- p.34 / Chapter 2.3.2 --- Aldrich Molecular Sieves (Organophilic) --- p.35 / Chapter 2.3.3 --- Other Adsorbents Used for Comparison --- p.35 / Chapter 2.4 --- Instrumental Analysis --- p.36 / Chapter 2.4.1 --- Photoacoustic Multi-gas Monitor --- p.36 / Chapter 2.4.2 --- X-Ray Diffraction Analysis --- p.42 / Chapter 2.4.3 --- Scanning Electron Microscopy --- p.42 / Chapter 2.4.4 --- UV-vis Diffuse Reflectance Spectroscopy --- p.42 / Chapter 2.4.5 --- Iso-electron Point Measurements --- p.43 / Chapter 2.5 --- Photocatalytic Degradation of Simple Alkanes by P25 Titanium Dioxide --- p.45 / Chapter 2.6 --- Photocatalytic Degradation of Gaseous Acetone over Organophilic Molecular Sieves-Supported Titanium Dioxide --- p.49 / Chapter 3. --- Results and Discussion / Chapter 3.1 --- Photocatalytic Degradation of Simple Alkanes by P25 Titanium Dioxide --- p.52 / Chapter 3.1.1 --- Rate of Photocatalytic Degradation of Simple Alkanes --- p.52 / Chapter 3.1.2 --- Summary of Rate of Photocatalytic Degradation of Simple Alkanes --- p.57 / Chapter 3.2 --- Photocatalytic Degradation of Gaseous Acetone over Organophilic Molecular Sieves-Supported Titanium Dioxide --- p.58 / Chapter 3.2.1 --- The Adsorption Ability of Various Adsorbents --- p.58 / Chapter 3.2.2 --- XRD Pattern Measurement --- p.60 / Chapter 3.2.3 --- Scanning Electron Microscopy --- p.64 / Chapter 3.2.4 --- UV-vis Diffuse Reflectance Spectroscopy --- p.65 / Chapter 3.2.5 --- Iso-electron Point Measurements --- p.67 / Chapter 3.2.6 --- Photocatalytic Activity of Various Catalysts --- p.69 / Chapter 4. --- Conclusion --- p.76 / Bibliography --- p.78 / Appendix / "A Demonstration of Photocatalytic Degradation by Gaseous Organic Pollutant, Dichloromethane " --- p.83

by Chan Shuk Mei. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2002. / Includes bibliographical references (leaves 138-149). / Abstracts in English and Chinese. / Acknowledgements --- p.i / Abstracts --- p.ii / Contents --- p.vi / List of figures --- p.xi / List of plates --- p.xiv / List of tables --- p.xv / Abbreviations --- p.xvi / Chapter 1. --- Introduction --- p.1 / Chapter 1.1 --- Pentachlorophenol --- p.1 / Chapter 1.1.1 --- Characteristics of pentachlorophenol --- p.1 / Chapter 1.1.2 --- Application of pentachlorophenol --- p.4 / Chapter 1.1.3 --- The fate of pentachlorophenol in environment --- p.5 / Chapter 1.1.4 --- The toxicity of pentachlorophenol --- p.9 / Chapter 1.1.5 --- Remediation of pentachlorophenol --- p.13 / Chapter 1.1.5.1 --- Physical treatment / Chapter 1.1.5.2 --- Chemical treatment / Chapter 1.1.5.3 --- Biological treatment / Chapter 1.1.5.4 --- Alternative for combining two treatments / Chapter 1.2 --- Biosorbents --- p.18 / Chapter 1.2.1 --- Chitin and chitosan --- p.21 / Chapter 1.2.1.1 --- History of chitin and chitosan --- p.21 / Chapter 1.2.1.2 --- Structures of chitin and chitosan --- p.21 / Chapter 1.2.1.3 --- Sources of chitin and chitosan --- p.23 / Chapter 1.2.1.4 --- Application of chitin and chitosan --- p.26 / Chapter 1.2.1.5 --- Study on PCP removal by chitinous material --- p.28 / Chapter 1.2.2 --- Factors affecting biosorption --- p.29 / Chapter 1.2.2.1 --- Solution pH --- p.29 / Chapter 1.2.2.2 --- Concentration of biosorbent --- p.30 / Chapter 1.2.2.3 --- Retention time --- p.31 / Chapter 1.2.2.4 --- Temperature --- p.32 / Chapter 1.2.2.5 --- Agitation rate --- p.32 / Chapter 1.2.2.6 --- Initial sorbate concentration --- p.33 / Chapter 1.2.3 --- Modeling of biosorption --- p.33 / Chapter 1.2.3.1 --- Langmuir adsorption model --- p.34 / Chapter 1.2.3.2 --- Freundlich adsorption model --- p.34 / Chapter 1.3 --- Photocatalytic degradation --- p.35 / Chapter 1.3.1 --- Titanium dioxide --- p.36 / Chapter 1.3.2 --- Mechanism of photocatalytic oxidation using photocatalyst TiO2 --- p.36 / Chapter 1.3.3 --- Advantages of photocatalytic oxidation with Ti02 and H2O2 --- p.41 / Chapter 1.3.4 --- Degradation of PCP by photocatalytic oxidation --- p.41 / Chapter 2. --- Objectives --- p.45 / Chapter 3. --- Materials and methods --- p.46 / Chapter 3.1 --- Biosorbents --- p.46 / Chapter 3.1.1 --- Production of biosorbents --- p.46 / Chapter 3.1.2 --- Scanning electron microscope of biosorbents --- p.48 / Chapter 3.1.3 --- Pretreatment of biosorbents --- p.48 / Chapter 3.2 --- Pentachlorophenol preparation --- p.48 / Chapter 3.3 --- Batch biosorption experiment --- p.48 / Chapter 3.3.1 --- Quantification of pentachlorophenol by HPLC --- p.51 / Chapter 3.3.2 --- Data analysis for biosorption --- p.51 / Chapter 3.3.3 --- Selection of optimal conditions for batch PCP adsorption --- p.52 / Chapter 3.3.3.1 --- Effect of initial pH and biosorbent concentration --- p.52 / Chapter 3.3.3.2 --- Improvement on pH effect and biosorbent concentration --- p.52 / Chapter 3.3.3.3 --- Effect of temperature --- p.53 / Chapter 3.3.3.4 --- Effect of agitation rate --- p.53 / Chapter 3.3.4 --- Effect of initial PCP concentration and biosorbent concentration --- p.53 / Chapter 3.3.4.1 --- Adsorption isotherm --- p.54 / Chapter 3.4 --- Photocatalytic oxidation --- p.54 / Chapter 3.4.1 --- Reaction mixture solution --- p.54 / Chapter 3.4.2 --- Photocatalytic reactor --- p.55 / Chapter 3.4.3 --- Batch photocatalytic oxidation system --- p.55 / Chapter 3.4.4 --- Selection of extraction solvent --- p.59 / Chapter 3.4.5 --- Extraction efficiency --- p.59 / Chapter 3.4.6 --- Data analysis for PCO --- p.60 / Chapter 3.4.7 --- Irradiation time --- p.60 / Chapter 3.4.8 --- Determination of hydrogen peroxide concentration --- p.61 / Chapter 3.4.9 --- Effect of biosorbent concentration in PCO --- p.61 / Chapter 3.4.10 --- Effect of PCP amount on biosorbent in PCO --- p.61 / Chapter 3.4.11 --- Determination of chloride ion concentration and total organic carbon during PCO --- p.62 / Chapter 3.4.12 --- Identification the intermediates of PCP degradation by PCO --- p.62 / Chapter 3.4.13 --- Evaluation of the change of PCO treated biosorbents --- p.63 / Chapter 3.4.13.1 --- Chitin assay --- p.64 / Chapter 3.4.13.2 --- Diffuse reflectance Fourier transform infra-red spectroscopy --- p.64 / Chapter 3.4.13.3 --- Protein assay --- p.66 / Chapter 3.4.13.4 --- Biosorption efficiency --- p.66 / Chapter 3.4.14 --- Multiple biosorption and PCO cycles of PCP --- p.66 / Chapter 3.4.15 --- Evaluation for the toxicity change of PCP adsorbed biosorbents during PCO --- p.67 / Chapter 4. --- Results --- p.68 / Chapter 4.1 --- Batch biosorption experiment --- p.68 / Chapter 4.1.1 --- Selection of optimal conditions for batch PCP adsorption --- p.68 / Chapter 4.1.1.1 --- Effect of initial pH and biosorbent concentration --- p.68 / Chapter 4.1.1.2 --- Effect of Tris buffer and biosorbent concentrations --- p.73 / Chapter 4.1.1.3 --- Effect of temperature --- p.73 / Chapter 4.1.1.4 --- Effect of agitation rate --- p.73 / Chapter 4.1.2 --- Effect of initial PCP concentration and biosorbent concentration --- p.81 / Chapter 4.1.2.1 --- Adsorption isotherm --- p.82 / Chapter 4.2 --- Photocatalytic oxidation --- p.88 / Chapter 4.2.1 --- Selection of extraction solvent --- p.88 / Chapter 4.2.2 --- Determination of hydrogen peroxide concentration --- p.88 / Chapter 4.2.3 --- Effect of biosorbent concentration in PCO --- p.88 / Chapter 4.2.4 --- Effect of PCP amount on biosorbent in PCO --- p.94 / Chapter 4.2.5 --- Determination of chloride ion concentration and total organic carbon during PCO --- p.98 / Chapter 4.2.6 --- Identification the intermediates of PCP degradation by PCO --- p.102 / Chapter 4.2.7 --- Evaluation of the change of PCO treated biosorbents --- p.102 / Chapter 4.2.7.1 --- Chitin assay --- p.102 / Chapter 4.2.7.2 --- Diffuse reflectance Fourier transform infra-red spectroscopy --- p.102 / Chapter 4.2.7.3 --- Protein assay --- p.102 / Chapter 4.2.7.4 --- Biosorption efficiency --- p.109 / Chapter 4.2.8 --- Multiple biosorption and PCO cycles of PCP --- p.109 / Chapter 4.2.9 --- Evaluation for the toxicity change of PCP adsorbed biosorbents during PCO --- p.109 / Chapter 5. --- Discussion --- p.115 / Chapter 5.1 --- Batch biosorption experiment --- p.115 / Chapter 5.1.1 --- Selection of optimal conditions for batch PCP adsorption --- p.115 / Chapter 5.1.1.1 --- Effect of initial pH --- p.115 / Chapter 5.1.1.2 --- Effect of Tris buffer and biosorbent concentrations --- p.118 / Chapter 5.1.1.3 --- Retention time --- p.119 / Chapter 5.1.1.4 --- Effect of temperature --- p.120 / Chapter 5.1.1.5 --- Effect of agitation rate --- p.121 / Chapter 5.1.2 --- Effect of initial PCP concentration and biosorbent concentration --- p.121 / Chapter 5.1.2.1 --- Modeling of biosorption --- p.122 / Chapter 5.2 --- Photocatalytic oxidation --- p.123 / Chapter 5.2.1 --- Selection of extraction solvent --- p.124 / Chapter 5.2.2 --- Determination of hydrogen peroxide concentration --- p.124 / Chapter 5.2.3 --- Effect of biosorbent concentration in PCO --- p.125 / Chapter 5.2.4 --- Effect of PCP amount on biosorbent in PCO --- p.127 / Chapter 5.2.5 --- Determination of chloride ion concentration and total organic carbon during PCO --- p.127 / Chapter 5.2.6 --- Identification the intermediates of PCP degradation by PCO --- p.128 / Chapter 5.2.7 --- Evaluation of the change of PCO treated biosorbents --- p.128 / Chapter 5.2.7.1 --- Chitin assay --- p.129 / Chapter 5.2.7.2 --- Diffuse reflectance Fourier transform infra-red spectroscopy --- p.129 / Chapter 5.2.7.3 --- Protein assay --- p.131 / Chapter 5.2.7.4 --- Biosorption efficiency --- p.131 / Chapter 5.2.8 --- Multiple biosorption and PCO cycles of PCP --- p.132 / Chapter 5.2.9 --- Evaluation for the toxicity change of PCP adsorbed biosorbents during PCO --- p.132 / Chapter 6. --- Conclusion --- p.134 / Chapter 7. --- Recommendation --- p.137 / Chapter 8. --- References --- p.138

Este trabalho descreve a síntese e caracterização de polímeros de coordenação (PC) e sua aplicação como fotocatalisadores heterogêneos ativos sob a radiação visível, visando a degradação de compostos orgânicos em água. Problemas ambientais têm ocupado posição de destaque na sociedade contemporânea. Dentre eles, o uso de combustíveis fósseis e a remoção de compostos poluentes do meio ambiente têm merecido especial atenção. Uma das alternativas mais indicadas como substituinte dos combustíveis fósseis é a energia solar, por ser limpa, renovável e presente em todo o planeta. O estudo de materiais fotoativos é essencial para aproveitar ao máximo essa fonte. A fotocatálise é um processo que utiliza a energia luminosa para realizar reações químicas. Os PC têm mostrado ótimos resultados na área. Esses são compostos poliméricos cujos monômeros são unidades de coordenação. Neste trabalho foram sintetizados PC formados por diferentes metais de transição e ligantes orgânicos. Dentre eles destacam-se níquel e benzenodicarboxilato (Ni-BDC). Os materiais foram caracterizados por FTIR, DRX, adsorção-dessorção de N2, DRS, TGA, MEV e ICP-OES. Os resultados sugerem a formação de PC inéditos, dotados de sítios de coordenação insaturados, com boa estabilidade térmica, porém com estabilidade em meio aquoso inferior. O ensaio de degradação fotocatalítica de corante evidencia que os materiais são fotoativos na luz visível, apesar da descoloração não ser completa. Este resultado é interessante, pois polímeros de coordenação de níquel ainda são pouco estudados como fotocatalisadores, e esse é um metal barato e abundante. / This work describes the synthesis and characterization of coordination polymers (CP) and their application as heterogeneous photocatalysts, under visible radiation, in degradation of organic compounds in water. Environmental issues have taken prominent position in contemporary society. Among them, fossil fuel usage and removal of hazardous compounds deserve special attention. One of the best alternatives to replace fossil fuels is the solar power, which is clean, renewable and ubiquitous throughout the planet. Research on photoactive materials is essential to improve this energy source use. Heterogeneous photocatalysis process uses light energy to induce chemical reactions. CP are exhibiting remarkable results in the field. These are polymeric compounds with coordination units as monomers. In the present work, CP based on different transition metals and organic ligands were synthesized, such as nickel benzenedicarboxylate (Ni-BDC). The materials were characterized by FTIR, XRD, N2 adsorption-desorption, DRS, TGA, SEM and ICPOES. The results suggest the formation of novel CP, endowed with unsaturated metal sites and good thermal stability, however with low stability in aqueous medium. The photocatalytic dye degradation experiments indicate the materials are photoactive under visible light, although the discoloration was not complete. This is an interesting result, considering that the research on nickel coordination polymers as photocatalysts is still scarce.

Nanocatalysis has emerged in the last decades as an interface between homogeneous and heterogeneous catalysis, offering simple solutions to problems that conventional materials have not been able to solve. In fact, nanocatalyst design permits to obtain structures with high superficial area, reactivity and stability, and at the same time presenting good selectivity and facility of separation from reaction mixtures. In this work, we prepared hybrid structures comprising gold, palladium and silver nanoparticles (Au, Pd and Ag NPs), titanate nanosheets (TixO2), graphene oxide (GO), and partially reduced graphene oxide (prGO). We focused on bi- and tri-components hybrids, namely TixO2, M/(pr)GO and M/TixO2/(pr)GO (M = Au, Pd or Ag) and developed facile, versatile and environment-friendly preparation methods with an emphasis on control over physicochemical features such as size, shape and composition. In order to exploit the catalytic applications, we employed the reduction of 4-nitrophenol as a model reaction, followed by visible-light assisted oxidation of p-aminothiophenol (PATP). With these tests, we unraveled metal-support interactions and cooperative effects that render hybrid structures superior to their individual counterparts. / A nanocatálise surgiu nas últimas décadas como uma interface entre catálise homogênea e heterogênea, oferecendo soluções simples a problemas que os materiais convencionais não conseguiram resolver. De fato, o design de nanocatalisadores permite obter estruturas com grande área superficial, reatividade e estabilidade, e ao mesmo tempo apresentando boa seletividade e facilidade de separação de misturas reacionais. Neste trabalho apresentamos a preparação de estruturas híbridas compostas por nanopartículas de ouro, paládio e prata (Au, Pd e Ag NPs), nanofolhas de titanato (TixO2), óxido de grafeno (GO) e óxido de grafeno parcialmente reduzido (prGO). Focamos em híbridos do tipo M/TixO2, M/(pr)GO e M/TixO2/(pr)GO (M = Au, Pd ou Ag) e desenvolvemos métodos de preparação simples, versáteis e ambientalmente amigáveis, com ênfase no controle sobre tamanho, forma e composição. Para explorar as potencialidades catalíticas utilizamos a redução do 4-nitrofenol como reação modelo, e em seguida a oxidação assistida por luz do p-aminotiofenol (PATP). Com esses testes, investigamos interações metal-suporte e efeitos cooperativos que tornam as estruturas hibridas superiores a cada um dos materiais que as compõem.

在本篇論文中，我們成功地在透明導電襯底上製備了一系列準一維納米材料陣列。我們首先製備了氧化鋅納米線陣列，然後把它們用作氧化鋅/硒化鎘核殼納米線纜陣列中的核以及合成硒化鎘和碲化鎘納米管陣列所需的犧牲模板。最後，金納米管陣列則是利用之前製備的硒化鎘納米管陣列為模板合成的。氧化鋅納米線陣列是通過高溫的熱蒸法和低溫的水熱法製備的。水熱法製備的氧化鋅納米線陣列的電導高於熱蒸法製備的氧化鋅納米線陣列，這使得水熱法製備的氧化鋅納米線更適合採用與電相關的後續處理方法。當氧化鋅納米線陣列被用作犧牲模板來製備納米管時，水熱法製備的氧化鋅納米線能被輕易地完全去除。基於這些認識，我們主要採用電化學沉積法在水熱法製備的氧化鋅納米線陣列表面沉積硒化鎘，得到了氧化鋅/硒化鎘核殼納米線纜陣列。接下來，我們將納米線纜陣列光電極和沉積了鉑催化劑的對電極組裝成三文治結構的太陽能電池。研究發現，採用多硫電解液的電池性能比碘基電解液的電池好，其中成分為1摩爾每升硫化鈉，1摩爾每升硫和1摩爾每升氫氧化鈉的多硫電解液的電池效率最高。當去除電化學沉積法生長的氧化鋅/硒化鎘和氧化鋅/碲化鎘核殼納米線纜陣列中的氧化鋅核以後，便在導電襯底上得到了硒化鎘和碲化鎘的納米管陣列。儘管兩種納米管陣列都對可見光有很強的吸收，但是，硒化鎘納米管陣列相比碲化鎘納米管陣列，表現出較高的光響應和較好的光催化降解亞甲基藍的活性。這是因為該樣品中的光生載流子能有效分離，同時能參與化學反應的表面積也較大。最後，我們選用硒化鎘納米管陣列作為模板，利用化學方法製備了金納米管陣列。金納米管的尺寸可以通過控制硒化鎘納米管模板來加以調節。當我們將具有拉曼活性的4-巰基苯甲酸分子吸附到金納米管的表面時，其拉曼散射相比未吸附時，顯著地增強了約四個數量級，如此大的提高來源於金納米管表面附近的局域電場增強效應。 / In this thesis, we demonstrated the synthesis of a series of pseudo-one-dimensional nanostructure arrays on transparent conducting substrates. We started with ZnO nanowire arrays, which were then served as the core for the ZnO/CdSe core/shell nanocable arrays formation. Further taking the ZnO as sacrificial templates led to the formation of CdSe (and CdTe) nanotube arrays. Finally, Au nanotube arrays were fabricated using the CdSe nanotube arrays as the template. ZnO nanowire arrays were synthesized via high-temperature thermal evaporation method (TE) and low temperature hydrothermal method (HT). The electrical conductivity of HT samples on the substrates was higher than that of the TE counterparts, making it attractive for further electrical-based processing. When serving as the sacrificial templates for nanotube fabrication, HT nanowires can be completely removed with ease. Based on these understanding, ZnO/CdSe core/shell nanocable arrays were obtained mainly via electrochemical deposition of CdSe on HT ZnO nanowire arrays. Nanocable-array-photoelectrode was assembled with a Pt-coated counter electrode into a sandwiched solar cell. Polysulfide electrolytes with various compositions were found to work better than iodine-based ones for such cells, and the cell with the polysulfide electrolyte containing 1 M Na₂S, 1 M S and 1 M NaOH showed highest efficiency. Removal of the ZnO cores in the electrodeposited ZnO/CdSe and ZnO/CdTe nanocable arrays left CdSe and CdTe nanotube arrays on the conducting substrate. Although strong visible-light absorption was observed from both two nanotube arrays, higher photocurrent and better photocatalytic degradation activity of methlyene blue were recorded from CdSe-nanotube-array samples (as compared to the CdTe ones), owing to effective charge separation and large surface area for chemical reactions. Lastly, Au nanotube arrays were synthesized via chemical method using CdSe nanotube arrays as the template. The dimensions of the Au nanotubes, as replicated from CdSe nanotubes, were tunable. When absorbed on the Au nanotube arrays surface, the Raman scattering of 4-mercaptobenzoic acid (a Raman-active molecule) was greatly enhanced for~4 orders of magnitude compared to the signals from the dry powder of the same molecule. Such large increase was due to the strong local electrical field enhancement near the Au nanotubes surface. / Detailed summary in vernacular field only. / Zhu, Haojun = 準一維納米結構在光伏、光催化及等離子體激元方面的應用 / 朱浩君. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2012. / Includes bibliographical references (leaves 141-168). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese. / Abstracts in English and Chinese. / Zhu, Haojun = Zhun yi wei na mi jie gou zai guang fu, guang cui hua ji deng li zi ti ji yuan fang mian de ying yong / Zhu Haojun. / Abstract --- p.i / 摘要 --- p.iii / Acknowledgements --- p.iv / Contents --- p.v / List of Figures --- p.viii / List of Tables --- p.xviii / Chapter Chapter 1 --- Introductions --- p.1 / Chapter Chapter 2 --- Background --- p.4 / Chapter 2.1. --- Nanostructured Photovoltaic (PV) Solar Cells --- p.4 / Chapter 2.1.1. --- Fundamental physics of nanostructures for solar cell applications --- p.5 / Chapter 2.1.2. --- Inorganic nano-architectures for PV cells --- p.9 / Chapter 2.2. --- Nanostructures for Photocatalytic Degradation of Organic Pollutants --- p.18 / Chapter 2.2.1 --- Overview of photocatalytic degradation of organic pollutants --- p.19 / Chapter 2.2.2 --- Photocatalysis under visible light illumination --- p.24 / Chapter 2.3. --- Plamonic Noble Metal Nanostructures --- p.29 / Chapter 2.3.1 --- Surface plasmons of noble metal nanostructures --- p.29 / Chapter 2.3.2 --- Applications of plasmonic noble metal nanostructures in solar energy conversion and sensing --- p.35 / Chapter Chapter 3 --- Methodologies and Instrumentations --- p.45 / Chapter 3.1. --- Materials Growth Methodologies --- p.45 / Chapter 3.1.1. --- Thermal evaporation (TE) methods --- p.45 / Chapter 3.1.2. --- Hydrothermal (HT) methods --- p.47 / Chapter 3.1.3. --- Electrodeposition (ED) methods --- p.49 / Chapter 3.1.4. --- Prototype solar cells assemble --- p.52 / Chapter 3.2. --- Characterization Techniques --- p.53 / Chapter 3.2.1. --- Morphological, structural, and compositional analysis using electron microscopy based techniques --- p.53 / Chapter 3.2.2. --- Photoelectrochemical (PEC) performance test --- p.63 / Chapter 3.2.3. --- Photocatalytic degradation of organic pollutants --- p.65 / Chapter 3.2.4. --- Single-particle scattering imaging and spectroscopy --- p.67 / Chapter Chapter 4 --- ZnO Nanowire Arrays on Conducting Substrates -- A Comparison on the Growth Methodology --- p.71 / Chapter 4.1. --- Introduction --- p.71 / Chapter 4.2. --- Experimental --- p.72 / Chapter 4.3. --- Results and Discussions --- p.75 / Chapter 4.3.1 --- Morphologies, crystal structures and chemical compositions --- p.75 / Chapter 4.3.2 --- ZnO nanowire arrays used as electrodes --- p.80 / Chapter 4.3.3 --- ZnO nanowire arrays used as sacrificial templates in electroplating . --- p.85 / Chapter 4.4. --- Conclusions --- p.88 / Chapter Chapter 5 --- ZnO-core/CdSe-shell Nanocable Arrays for Photovoltaic Solar Cells --- p.89 / Chapter 5.1. --- Introduction --- p.89 / Chapter 5.2. --- Experimental --- p.90 / Chapter 5.3. --- Results and Discussions --- p.93 / Chapter 5.3.1 --- Synthesis of the ZnO-core/CdSe-shell nanocable arrays on ITO/glass --- p.93 / Chapter 5.3.2 --- The photovoltaic (PV) performance --- p.100 / Chapter 5.4. --- Conclusions --- p.107 / Chapter Chapter 6 --- CdSe and CdTe Nanotube Arrays as Visible-light-driven Photocatalyst for Organic Pollutant Degradation --- p.108 / Chapter 6.1. --- Introduction --- p.108 / Chapter 6.2. --- Experimental --- p.109 / Chapter 6.3. --- Results and Discussions --- p.112 / Chapter 6.3.1. --- Morphology, crystal structure, and chemical composition of the nanotube arrays --- p.112 / Chapter 6.3.2. --- Optical properties --- p.116 / Chapter 6.3.3. --- Photoelectrochemical (PEC) performance --- p.117 / Chapter 6.3.4. --- Photocatalytic activities --- p.120 / Chapter 6.4. --- Conclusions --- p.123 / Chapter Chapter 7 --- Fabrication of Au Nanotube Arrays and Their Plasmonic Properties --- p.124 / Chapter 7.1. --- Introduction --- p.124 / Chapter 7.2. --- Experimental --- p.125 / Chapter 7.3. --- Results and Discussions --- p.127 / Chapter 7.3.1. --- Morphology, crystalline structure, and chemical composition of Au nanotube arrays --- p.127 / Chapter 7.3.2. --- Au nanotube formation mechanism --- p.129 / Chapter 7.3.3. --- Plasmonic properties of Au nanotube arrays on ITO/glass substrates --- p.131 / Chapter 7.3.4. --- Plasmonic properties of single Au nanotubes --- p.133 / Chapter 7.3.5. --- Au nanotube arrays on ITO/glass as SERS substrates --- p.134 / Chapter 7.4. --- Conclusions --- p.138 / Chapter Chapter 8 --- Conclusions --- p.139 / Bibliography --- p.141

"The simultaneous degradation of five organic contaminants: 1,4 dioxane, n-nitrosodimethylamine, tris-2-chloroethyl phosphate, gemfibrozil, and 17β estradiol, was investigated using a 1 L batch water-jacketed UV photoreactor utilizing titanium dioxide (TiO2) nanoparticles (Degussa P-25) as a photocatalyst. The primary objectives of this research were: (1) to experimentally assess the feasibility of heterogeneous photocatalysis as a promising alternative for the degradation of organic compounds in water; and (2) to model the chemical reactions by the application of two different approaches based on adsorption – surface reactions (Langmuir–Hinshelwood) and its simplification to a first order rate reaction. These objectives were motivated by the lack of information regarding simultaneous degradation of organic compounds in different categories as found in real aqueous matrices, and generation of specific intermediates that could eventually represent a potential risk to the environment. Contaminants were chosen based on their occurrence in water sources, their representativeness of individual sub-categories, and their importance as part of the CCL3 as potential contaminants to be regulated. Contaminant degradation was evaluated over time, and the TiO2 concentration and solution pH were varied under constant UV irradiation, oxygen delivery rate, mixing gradient, and temperature. 

 Specific accomplishments of this study were: (1) reaction kinetics data were obtained from the UV/TiO2 experiments and showed the potential that this UV/TiO2 process has for effectively removing different types of organic compounds from water; (2) a good fit was obtained between photocatalytic reaction kinetics models and the contaminant data using pseudo first-order and Langmuir-Hinshelwood (L-H) models; (3) results of the analytical methods developed in this study were validated by measurements performed by a certified laboratory; (4) the reaction kinetic parameters obtained in this study were normalized to electrical energy per order, reactor volume and surface area of the photocatalyst in order to provide rate constants with wider applicability for scale-up to more complex systems; and (5) degradation intermediates from the oxidation process and from interaction among compounds were identified and possible pathways for their formation suggested. This research has provided a better understanding of the photocatalytic process for the removal of organic contaminants from complex aqueous matrices."