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postgraduate thesis: Metal oxide photocatalysis

TitleMetal oxide photocatalysis
Authors
Advisors
Advisor(s):Djurisic, A
Issue Date2013
PublisherThe University of Hong Kong (Pokfulam, Hong Kong)
Citation
Guo, M. [郭牧遥]. (2013). Metal oxide photocatalysis. (Thesis). University of Hong Kong, Pokfulam, Hong Kong SAR. Retrieved from http://dx.doi.org/10.5353/th_b5043445
AbstractPhotocatalysis has been attracting much research interest because of its wide applications in renewable energy and environmental remediation. Among the photocatalysts, metal oxide semiconductors are the best choice due to distinctive properties, durability and cost effectiveness. However, the mechanisms of photocatalysis are still not entirely clear and the photocatalytic activity of the metal oxide materials needs to be improved. Therefore, this thesis concentrates on the study of the photocatalytic mechanism and the factors affecting the photocatalytic activity. The photocatalysis of different commercial metal oxide nanoparticles has been studied. Different photocatalytic experiments have been designed to find out the mechanisms of photocatalysis. It is found that the dominant mechanism of photocatalysis is direct charge transfer between metal oxide and organic compounds. Reactive oxygen species, such as hydroxyl radicals also play a minor role in the photocatalysis. ZnO tetrapods were synthesized by evaporating Zn powder in the flow of Ar gas at high temperature in this study. They exhibit excellent photocatalytic activity. By the comparison between ZnO tetrapods and different ZnO nanoparticles, it is found that the photocatalytic activity of the metal oxide is strongly affected by the native defects, especially by the nonradiative defects. 1D TiO2 nanotubes and ZnO nanorods were synthesized by anodization and hydrothermal growth respectively. ZnO nanorods with alumina and titania shell were prepared by solution-based methods. These structures are interesting as supported catalysts, which is important for practical applications, since it enables simple removal of photocatalyst from treated water. The core shell structures are expected to improve the stability of ZnO. The results also imply that the photocatalytic avtivity of materials is affected by the native defects. Two different solution based methods hydrothermal growth and electrodeposition to grow CuxO layer were used. The hydrothermal grown CuxO exhibit excellent photocatalytic activity and good photocorrosion resistance. It was also found that the photocatalytic activity of the CuxO prepared by hydrothermal methods can be recovered by simple immersion of the sample into the precursor solution.
DegreeMaster of Philosophy
SubjectMetallic oxides.
Photocatalysis.
Dept/ProgramPhysics
Persistent Identifierhttp://hdl.handle.net/10722/184258

 

DC FieldValueLanguage
dc.contributor.advisorDjurisic, A-
dc.contributor.authorGuo, Muyao.-
dc.contributor.author郭牧遥.-
dc.date.accessioned2013-06-29T15:46:26Z-
dc.date.available2013-06-29T15:46:26Z-
dc.date.issued2013-
dc.identifier.citationGuo, M. [郭牧遥]. (2013). Metal oxide photocatalysis. (Thesis). University of Hong Kong, Pokfulam, Hong Kong SAR. Retrieved from http://dx.doi.org/10.5353/th_b5043445-
dc.identifier.urihttp://hdl.handle.net/10722/184258-
dc.description.abstractPhotocatalysis has been attracting much research interest because of its wide applications in renewable energy and environmental remediation. Among the photocatalysts, metal oxide semiconductors are the best choice due to distinctive properties, durability and cost effectiveness. However, the mechanisms of photocatalysis are still not entirely clear and the photocatalytic activity of the metal oxide materials needs to be improved. Therefore, this thesis concentrates on the study of the photocatalytic mechanism and the factors affecting the photocatalytic activity. The photocatalysis of different commercial metal oxide nanoparticles has been studied. Different photocatalytic experiments have been designed to find out the mechanisms of photocatalysis. It is found that the dominant mechanism of photocatalysis is direct charge transfer between metal oxide and organic compounds. Reactive oxygen species, such as hydroxyl radicals also play a minor role in the photocatalysis. ZnO tetrapods were synthesized by evaporating Zn powder in the flow of Ar gas at high temperature in this study. They exhibit excellent photocatalytic activity. By the comparison between ZnO tetrapods and different ZnO nanoparticles, it is found that the photocatalytic activity of the metal oxide is strongly affected by the native defects, especially by the nonradiative defects. 1D TiO2 nanotubes and ZnO nanorods were synthesized by anodization and hydrothermal growth respectively. ZnO nanorods with alumina and titania shell were prepared by solution-based methods. These structures are interesting as supported catalysts, which is important for practical applications, since it enables simple removal of photocatalyst from treated water. The core shell structures are expected to improve the stability of ZnO. The results also imply that the photocatalytic avtivity of materials is affected by the native defects. Two different solution based methods hydrothermal growth and electrodeposition to grow CuxO layer were used. The hydrothermal grown CuxO exhibit excellent photocatalytic activity and good photocorrosion resistance. It was also found that the photocatalytic activity of the CuxO prepared by hydrothermal methods can be recovered by simple immersion of the sample into the precursor solution.-
dc.languageeng-
dc.publisherThe University of Hong Kong (Pokfulam, Hong Kong)-
dc.relation.ispartofHKU Theses Online (HKUTO)-
dc.rightsThe author retains all proprietary rights, (such as patent rights) and the right to use in future works.-
dc.rightsCreative Commons: Attribution 3.0 Hong Kong License-
dc.source.urihttp://hub.hku.hk/bib/B50434457-
dc.subject.lcshMetallic oxides.-
dc.subject.lcshPhotocatalysis.-
dc.titleMetal oxide photocatalysis-
dc.typePG_Thesis-
dc.identifier.hkulb5043445-
dc.description.thesisnameMaster of Philosophy-
dc.description.thesislevelMaster-
dc.description.thesisdisciplinePhysics-
dc.description.naturepublished_or_final_version-
dc.identifier.doi10.5353/th_b5043445-
dc.date.hkucongregation2013-

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