Preparation, Characterization And Photocatalytic Activity Of Transition Metal-doped GaN, BiVO₄ And SnO₂ Photocatalysts

With the development of international industrialization, environmental problem are becoming more and more serious, especially the water pollution. Organic pollutant in the polluted water can be handled by photocatalytic technology. In this paper, undoped Ga N, Bi VO4 and Sn O2 semiconductor photocatalysts were prepared via some simple methods. The prepared photocatalysts were characterized by X-ray diffraction(XRD), scanning electron microscopy(SEM), energy-dispersive spectroscopy(EDS) and UV-vis reflectance spectroscopy(DRS). Their photocatalytic activity were evaluated by the photocatalytic degradation of Rhodamine-B(Rh B) solution under ultraviolet light or visiable light irradiation. The mechanism of changed photocatalytic activity was also discussed.(1) Nanocrystalline gallium nitride(Ga N) photocatalysts were prepared by the reaction of Ga2O3, NH4 Cl, metallic Mg powder in an autoclave at 650℃. The as prepared Ga N has weak photocatalytic activity, which can be significantly enhanced by doping transition metals ions. The highest photocatalytic degradation activity was observed when the content of Fe dopant is 1.0 wt%, which is almost 4 times higher than that of the undoped Ga N.(2) Bi VO4 visiable-light photocatalysts were prepared by the reaction of Bi(NO3)3 and NH4VO3 powder in a hydrothermal autoclave at 180℃. If sodium dodecyl sulfonate(SDS) powder was added to the raw meterial, Bi VO4 with the morphology of chrysanthemum can be prepared, whose photocatalytic activity can be slightly enhanced. In addition, its photocatalytic activity can also be slightly enhanced by doping Cu2+ and Co2+ with the contents less than 0.25 wt%. When these two methods are used at the same time, the photocatalytic activity of Bi VO4 can be greatly enhanced.(3)Sn O2 photocatalysts were prepared by the hydrolyzing reaction of Sn Cl4 in a hydrothermal autoclave at 220℃. The as prepared Sn O2 has moderate photocatalytic activity, but it can be significantly enhanced by doping transition metals ions. The highest photocatalytic degradation activity was observed when the content of Cr dopant is 1.5 wt%, which is about twice higher than that of the undoped Sn O2.