Synthesis And Photoelectric Conversion Properties Of Porous And Spherical TiO₂Micro/Nano Composite Materials

Energy and environment issues are facing tremendous challenges in the21stcentury human society. It is necessary to solve the increasingly serious energyshortages and environmental pollution. The most effective way to solve theseproblems should be developing the photoelectric functional materials which be usedto utilize the solar energy. Especially, the application of novel semiconductorphotoelectric functional materials in photoelectric conversion systems will be theefficient way for the conversion from solar energy to electrical energy or chemicalenergy.The previous study on semiconductor photoelectric materials mainly focusbulk-materials, micro-materials, nano-materials and micro-nano-composite materials.Especially, semiconductor nano-materials with excellent physical and chemicalproperties are used in the new generation of photoelectric transformation system.Traditional semiconductor materials such as TiO2and ZnO nanoparticles become themain research direction of micro-nano composite semiconductor materials due to itsgood photoelectric semiconductor properties. But these traditional materials still existsome problems in the actual application, such as narrow absorption band, lowquantum efficiency and low utilization rate of recycling. So the narrow band-gapsemiconductor and organic dye are used to sensitize TiO2and ZnO broadband gapsemiconductor, which constructing micro-nano composite structure to improvephotoelectric conversion efficiency of traditional material under visible light.Through the study of photogenerated charges separation process in themicro-nano composite photoelectric functional materials. we can learn more about itsphotoelectric conversion process and how to improve the properties of materials. It isuseful for establish a new photovoltaic system and understand the mechanism ofphotocatalytic.The research target of this thesis is to design and synthesis excellencemicro-nano composite material which own a good charge generation and separationability. The preparation of new materials used in high performance solar cell andvisible light catalytic degradation of organic pollutants. The charge transfer and separation process of micro-nano composite structure are influenced by many factors,So we take some mixing and sensitized methods to improve the performance of thematerials.The photovoltaic and photocurrent technology are used to research the propertiesof photogenerated charge and the mechanism of photogenerated charge was explainedin this thesis. In the experiments, a number of instruments are used for charaterize thematerials. Such as SEM、TEM、XRD and so on. This thesis,work including:1. A series of SrTiO3–TiO2microspheres with different porosities were preparedby a facile hydrothermal reaction method in the presence of Sr(OH)2and titaniumglycolate. The photogenerated charge separation and surface trapping process wasstudied by surface photovoltage (SPV) spectra and corresponding phase spectra.Compared with one-dimension nanowires, the SrTiO3–TiO2microspheres showstructural advantage in photocatalytic degradation under visible-light. The enhancedphotocurrent of Rhodamine B (RhB) sensitized SrTiO3–TiO2microspheres reveals thata photosensitization effect leads to the photodegradation process. According to theexperimental results, these SrTiO3–TiO2microspheres have great potential applicationsin photocatalytic decomposition or photoelectronic devices.2. A new TiO2photoanode consist of mesoporous TiO2microspheres was firstemployed to fabricate CdS sensitized quantum dot-sensitized solar cell (QDSC). Wehave used a hydrothermal method to synthesis the three-dimensional morphology ofmesoporous TiO2microspheres. Photoanodes consisting of monolayer mesoporousTiO2microspheresby by doctor blade technique which simplified the traditionalpreparation technology and provide good scattering ability on the surface of thephotoanode, as well as increases the adsorption amount of quantum dots(QDs) underthe same times of CBD. The experimenal results show that the sensitization ofhigh-surface-area TiO2electrode with QD layers increases the performance of the solarcell, resulting in2.63%efficiency. which exhibiting potential application in highlyefficient QDSCs.