Preparation,characterization And Activity Evaluation Of Composite Photocatalyst

Abstract: Fe-TiO₂ photocatalyst was prepared by sol-gel method using tetrabutyl titanate [Ti(OC4H9)4] as the titanium precursor. The composite photocatalyst Fe-TiO₂/TiO₂ were prepared by ball milling method. Orthorhombic Nb₂WO₈ was synthesized through solid reaction in Nb₂O₅-WO₃ system. Stoichiometric amounts of Nb₂O₅ and WO3 were mixed and heated in alundum crucible at 1100 oC for several hours. Heterojunction photocatalyst Nb₂WO₈/ZnO was prepared via ball milling using aqueous solution as the dispersant. heterostructure In₂O₃/In(OH)₃ photocatalyst was prepared by programmed thermal treatment of In(OH)₃ using In(NO₃)₃.9H₂O as the precursor. Various characterization methods such as X-ray power diffraction (XRD), UV–Vis diffuse reflectance spectroscopy (DRS), flourier transform infrared spectrometry (FT-IR) and transmission electron microscopy (TEM) were employed to investigate the structure, morphologies, and optical properties. The results show that doping Fe³⁺ into TiO₂ is more beneficial towards photocatalytic reduction rather than oxidation with the optimum amount level 0.05% (Fe/Ti molar ratio). After coupled between Fe-TiO₂ and TiO₂, both the photooxidation and photoreduction activities of the sample are enhanced. Amongst the composite Fe-TiO₂/TiO₂ samples, the Fe-TiO₂ (5.0wt.%)/TiO₂ sample exhibits the best photocatalytic activity; the photocatalytic activity of the Nb₂WO₈/ZnO was higher than that of ZnO. When the amount of doped Nb₂WO₈ was 10wt.% and the Nb₂WO₈/ZnO was ball milled for 9 h, the heterostructure Nb₂WO₈/ZnO show the optimal activity. When the composition of In(OH)₃ is less than 5wt.%, the photocatalytic activity of the heterostructure In₂O₃/In(OH)₃ is higher than single In₂O₃ and In(OH)₃. CuCr₂O₄ photocatalyst was successfully synthesized both by solid reaction and facile citric acid method. The feasibility of photoreduction of nitro-benzene using CuCr₂O₄ as the photocatalyst under UV illumination was confirmed. Effects of parameters of preparation conditions on the photocatalytic activity were investigated. The mechanisms of influence on the photocatalytic activity were also tentatively discussed.