Preparation And Photocatalvtic Study Of Multi-metal Oxide Nanostructures

In today’s society, in order to solve the two important problems of the energy shortage and environmental pollution that the human societies are facing, the research and application of clean and renewable energy technology is imminent. Under this background, solar energy and hydrogen energy are clean energy and have attracted more and more attention. Photocatalysis is very promising in the fields of photodegradation and photocatalytic water-splitting into hydrogen, but the traditional photocatalysts TiO2 only absorb the UV light due to its wide bandgap, which limit its application. WO3 and ZnFe2O4 are typical photocatalysts that have narrow band gap, and their corresponding bandgap are 2.5-3.0 eV and 1.8～2.0 eV. But their photocatalytic performance is relatively poor. In order to improve their photocatalytic performance, we modify the WO3 and ZnFe2O4 semiconductor materials, respectively. The main research results are described as follow:1. We prepared the Fe-doped WO3 nanostructures, ZnFe2O4 nanostructures and the ZnFe2O4/ZnO nanoheterostructures by using the multiple metal ions adsorption and carbon sphere template method, and analyzed the influence of compositional components, nanostructures and nanoheterostructures on their photodegratation of RhB and phenol as well as solar-driven water-splitting into hydrogen.2. The Fe-doped WO3 nanostructures were obtained by using a template method; the band gap of the Fe-doped WO3 nanostructures was facilely tunable by controlling the Fe contents, and thereby it could increase the absorption of visible light. And the density-functional theory (DFT) calculation revealed that the formation of impurity band in the band gap narrowed the band gap of the Fe-doped WO3 nanostructures. We still studied the influence of doping Fe content on the photocatalytic activity of the Fe-doped WO3 nanostructures, and analyzed the photocatalytic mechanism of the Fe-doped WO3 nanostructures and the reason why appropriate doping Fe content could improve the photocatalytic efficiency.3. The ZnFe2O4 nanostructures in ultrathin hollow sphere morphology were successfully synthesized. The nanoparticles’size of 10 nm and ultrahigh surface area could ramarkly improve the photocatalytic hydrogen production of nanostructures. In order to further improve the photocatalytic activitiy of nanostructures, we also prepared the ZnFe2O4/ZnO nanoheterostructures that had the same hollow sphere morphology. We studied the influence of grain size and compositional components on photocatalytic hydrogen rate, and analyzed the photocatalytic mechanism of the ZnFe2O4/ZnO nanoheterostructures, and found that these nanoheterostructures could effectively enhance the separation and transportation of photo-generated carriers, thereby improve the photocatalytic hydrogen rate.