Synthesis And Photoelectrocatalytic Properties Of Composite Materials Of Rutile TiO₂/Zno Nanowires

Environmental pollution and energy shortage are major problems to be solvedurgently by human in the21st century. Semiconductor TiO₂has the stability ofchemical properties, non-toxic to living organisms, strong oxidizing and reducing,and it can be directly used to the solar energy as a unique properties such to drive thereaction, therefore, it is an ideal photocatalyst to control environmental pollution andproduce clean energy. The excitation wavelength range of rutile TiO₂is relativelywide. So rutile TiO₂can response to the visible light leading to the separation ofcharges. It has good application prospects in visible light photocatalysis. However,the electrons and holes in rutile TiO₂surface are easy to recombine, so itsphotocatalytic performance is much lower than anatase TiO₂. In order to solve thisscientific problem, we apply rutile TiO₂to photoelectrocatalysis system. Usingnegative bias is conducive to the separation of electron-hole pairs, and the catalyticactivity of rutile TiO₂has been significantly improved. The rutile TiO₂/Tiheterojunction film prepared on Ti sheet as a base lead to upwards band bending ofTiO₂semiconductor, which is propitious to the diffusion of electrons and holes.Meanwhile we prepared the composite structures of rutile TiO₂/Ti heterojunctionfilm and ZnO nanowire arrays to improve the mobility of electrons, increase thespecific surface area, and inhibit the recombination of the electron-hole pairs, andthe photoelectric catalysis efficiency of films have been improved. The maincontents are as follows:a) The rutile TiO₂/Ti heterojunction film has been prepared by thermaloxidation on the Ti sheet. In the applied negative bias photoelectrocatalysis system,the rutile phase TiO₂film has good catalytic activity under visible light irradiation. Itis found that the degradation efficiency of dye in the negative bias system is greaterthan the positive bias. We explain this phenomenon by using the semiconductor bandbending mechanism. Finally we prove this mechanism by double-groove experimental research.b) We have prepared composite of rutile TiO₂film and ZnO nanowire arrays bychemical vapor deposition method on the metal Ti sheet for the first time. The aspectratio of ultra-long ZnO nanowire arrays grown on rutile TiO₂film is up to130. MetalTi sheet as the electrode substrate material is conductive. The composite is UV andvisible light-responsive photocatalyst and the specific surface area is greatlyimproved compared with the rutile phase TiO₂film. Meanwhile, single crystal ZnOnanowire is contribute significantly to the transmission of the electronic. Thesefactors make this composite is effective to degrade of organic pollutants by usingphotoelectrocatalysis system.c) We have prepared composite structure of rutile TiO₂film and ZnO nanocombby chemical vapor deposition method on the metal Ti sheet for the first time. It isfound that the thickness of Au catalyst determines the arrangement of ZnOnanostructures and the diameter of nanowire. The ZnO nanocomb arrays preparedwith20nmAu film as the catalyst is single crystal with uniform arrangement.