Preparation Of Novel Compound Semiconductor Photocatalyst And Their Photocatalytic Performance

Visible-light photocatalysis that can directly harvest energy from incoming solar energy offers a desirable way to solve energy shortage and environmental remediation. At present many researches focused on the ultraviolet-response semiconductor materials, such as TiO2, ZnO and so on, but the sunlight utilization rate of these materials is very low, and the photocatalytic activity is poor. So the crux of the photocatalytic technology research is to search novel visible-light-response photocatalyst. This experiment research concentrates on two kinds of novel semiconductor materials Ta3N5 and Ag3PO4, both of which have narrow band gap, wide visible absorption range, and strong photocatalytic activity as well. In this work, p-n heteroarchitecture Ag3PO4/Ta3N5 photocatalyst have been prepared and characterized. The performance of visible-light photocatalytic activity and sterilization have also been tested, and the details as follows:1. The Ta3N5 nanorods aggregation was successfully prepared by the hydrothermal method and nitriding treatment method. And we also determined the optimum reaction conditions:the concentration of HF was 0.4 mol/L, hot water temperature was 240℃, the processing time of 12 h and nitriding processing temperature 850℃.The sample was pure orthogonal Ta3N5, and had anobvious morphology of three-dimensional nanorods aggregation with diameters of 40～60 nm and lengths of 250-350 nm. The Ta3N5 film which was prepared a blade coating showed high photocatalytic degradation activity for the degradation of MB and 1-naphthol.2. A novel 3D p-n heteroarchitecture Ag3PO4Ta3N5 composite photocatalyst with double visible-light-response characteristics has been prepared using an in-situ template-free precipitation methodand characterized by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy and transmission electron microscopy. UV-Vis diffuse reflectance spectroscopy, photoluminescence spectra and electrochemical impedance spectrum results revealed that Ag3PO/Ta3N5 composite had excellent sunlight utilization, efficient separation and transfer characteristics of photogenerated electrons and holes.3. It is found that the fascinating Ag3PO4/Ta3N5 exhibited high superior photoactivity and photostability compared to bare Ag3PO4 and Ta3N5 for the degradation of RhB under visible light irradiation. The improved performance of the composite is primarily attributable to sufficient visible-light harvesting, efficient charge separation and transfer of photogenerated electrons and holes resulting from matched energy bandgaps and sufficient p-n heterointerfaces between Ag3PO4 and Ta3N5. The quenching effects of different scavengers demonstrate that the reactive h+ and ·O2- species played a major role in the photodegradation process.4. Ag3PO4/Ta3N5 composite photocatalyst has efficient antibacterial performance to Escherichia coli. The bactericidal rate can reach 98.6% after 10min visible light irradiation. The antibacterial mechanism of Ag3PO4/Ta3N5 composite photocatalyst is partly a result of Ag ion, more from the super oxygen groups produced in the photocatalytic process which can destroy the structure of bacteria, so as to kill bacteria.