A Study On Synthesis And Photocatalytic Properties Of Nanocomposites

Layered photocatalytic nanocomposite synthesized by utilizing nanospaces of layered compounds to fabricate semiconductors nanopaticles has received ever-increasing attention in field of photocatalytic science over recent years. The photocatalytic action of layered nanocomposite semiconductor is based on the charge rapidly transferring from guest to guest or from guest to host layer to decrease electron-hole recombination, so as to improve photocatalytic activity. Especially, this material can be recycled easily, and has potential applications in the area of environmental engineering.In this thesis, we have synthesized a layered type compound HTaWOg · xH2O (x=0-1.5) successfully. And then, HTaWO6/(TiO2, Pt), HTaWO6/(Cdo.8Zno.2S, Pt) and HTaWO6/MxOy(Cr2O3, CuO, Fe2O3, NiO and MnO2) nanocomposites were prepared by using sol-gel, coprecipitation and hydrothermal methods with semiconductor ultrafine particles highly dispersing in the interlayer of HTaWO6. These samples were characterized by TG-DTA, XRD, DRS, Specific surface area analysis, Atomic absorption spectroanalysis and Fluorescence analysis. The photocatalytic activity of the catalysts was tested with methyl orange as objective decomposition substance. As a result, the photocatalytic activities of HTaWOe/TiO2 and HTaWO6/Cd0.8Zn0.2S were superior to that of pristine samples, and they were greatly increased with co-doping Pt particles in the interlayer. The photocatalytic activity of HTaWO6/(TiO2, Pt) was higher than TiO2 (P-25), which maybe due to that the surface area of HTaWO6/(TiO2, Pt) was 28 times as HTaWO6's. Under the conditions of our experiments, first reaction rate of photocatalytic degradation of HTaWO6/(TiO2, Pt) was 0.0089 min-1. It also found that incorporation of Cd0.8Zn0.2S in the interlayer region of HTaWO6 was possible to suppress the photocorrosion of Cdo.gZn0.2S. The photocatalytic activity of HTaWO6/MxOy (Cr2O3, CuO, Fe2O3, NiO and MnO2) was, more or less, higher than HTaWO6, which the mechanism of photocatalytic reaction was not very clear now, and will be further studied.