Preparation And Photoelectric Properties Of Metal Oxides With Complex Structure

Environmental pollution has been one of the greatest two challenges facing mankind. To address the problems, many approaches have been developed. Semiconductor-mediated photocatalysis is an attractive environmental remediation technology to treat pollutants both in gas and in liquid phase because it makes use of the clean, safe, and renewable sunlight to solve environmental problems. However, the conventional TiO2-based photocatalysts suffer from narrow photoresponse, low quantum yield and small specific surface area. To more efficiently use the solar energy this thesis focuses on developing some visible light photocatalysts including PANI sensitized N-TiO2inverse opals and novel hierarchical flower-like Bi2O3microspheres.PANI sensitized N-TiO2inverse opals were prepared by sol-gel method and natural deposition method, and photoelectrochemical properties and photocatalytic performance about degradation of Methylene blue of this inverse opal film were studied; In addition, novel hierarchical flower-like Bi2O3microspheres were successfully synthesized via a solvothermal process in the presence of ethylene glycol.The main contents are summarized as follows:1. In the first part, a facile emulsion polymerization approach was developed to synthesize highly monodisperse polystyrene (PS) spheres using potassium persulfate as the initiator and polyvinylpyrrolidone (PVP) as a stabilizer, respectively. The PS colloidal photonic crystals films were prepared from aqueous suspensions by vertical deposition at45℃. The PS colloidal photonic crystals films were fabricated on a microscope slides or FTO glass substrate by using vertical deposition method at45℃. Then a sol-gel process was used to assemble N-TiO2onto the PS photonic crystals films, followed by a calcination process to remove PS templates. Moreover, PANI was applied to sensitize the as-prepared nitrogen doped titanium oxide inverse opal structure. UV-Vis diffuser reflectance spectrum indicates that PANI-sensitized N-TiO2inverse opal films exhibit visible light absorption ability. It is note worthy that the photocurrent density and photocatalytic efficiency are enhanced by9times and1.8times through PANI sensitization in comparison to that of a N-TiO2inverse opal film.2. The second part describes a novel porous flower-like Bi2O3microsphere photocatalyst synthesized via a solvothermal process in the presence of ethylene glycol. The Bi2O3microspheres have diameters around1.3μm and nanosheet-assembled structures. These nanosheets have thickness of20-30nm and are aligned to the spherical surface, pointing toward a common inner center. The optical properties, Brunauer-Emmett-Teller (BET) surface areas and photocatalytic activities of the different Bi2O3hierarchical structures were also evaluated. The photocatalytic performances of the microspheres were evaluated by examining the degradation of RhB. The samples show excellent photocatalytic activity such that RhB degradation efficiency is approach97%at an irradiation time of60min under Xe lamp irradiation.