Synthesis And Properties Study Of Bismuth-based And Silver-based Photocatalysts

With the rapid development of the national industry, environmental pollution and energy shortage are becoming more and more severe. It is urgent to develop a new type of visible light responsive photocatalyst. In this paper, α-Bi2O3, Ag3PO4 photocatalyst were prepared by different methods, and the crystal structures, morphologies and optical properties of the samples were characterized by X-ray diffraction(XRD), scanning electron microscopy(SEM), and ultraviolet-visible diffuse reflectance spectroscopy(UV-Vis DRS) respectively. At the same time, because of the problem of poor stability, serious corrosion and high cost of Ag3PO4, two kinds of composite materials, Ag3PO4-Bi2WO6 and Ag3PO4-BiPO4, were prepared in this paper and their photocatalytic activity and cyclic stability were studied.The main contents of this paper are as follows:1. The α-Bi2O3 microncrystals with different morphologies were successfully synthesized by solvothermal method in various alcoholic solution(methanol, ethanol, isopropanol). The research shows that the morphology of the crystal is affected by the type and amount of alcohol, but the change of the ratio of methanol to water volume is very obvious. With the increase of methanol to water volume ratio, crystal morphology from oblique prism nanorods gradually evolved into a diamond-shaped sheet structure. The diamond platy structure of α-Bi2O3 was used in the degradation of MO, the photocatalytic degradation efficiency of 68.7%. After five cycles of regeneration, the efficiency of photocatalytic degradation can still reach more than 65%.2. With different alcohol as solvent, Ag3PO4 photocatalyst was prepared by alcohol assisted hydrothermal method. It was found that the morphology, dispersion and specific surface area of the Ag3PO4 were affected by different alcohols, and the photocatalytic properties of the catalysts were also affected. By the degradation of RhB in the visible light, the ability of polyhedral Ag3PO4 prepared by ethanol to degrade RhB was the best. After three cycles, the efficiency of photo degradation was reduced, which showed that the stability of the obtained Ag3PO4 was relatively poor, but the stability of polyhedral Ag3PO4 was relatively good.3. Ag3PO4-BiPO4 heterojunction as photocatalys were prepared by combining hydrothermal method and precipitation method. It consists of spherical particles in diameter 300-400 nm Ag3PO4 and about 150 nm in width, 3 μm in length BiPO4 micron rod by self assembling. When the molar ratio of Ag3PO4 to BiPO4 is 1:5, degradation of RhB under visible light, the obtained heterogeneous photocatalyst exhibited the highest catalytic activity, and the degradation rate of RhB in 90 min was 96%. After five cycles, the degradation rate can reach 90%.4. Ag3PO4-Bi2WO6 composite material as photocatalys were prepared by combining hydrothermal method and precipitation method. By the degradation of organic dye RhB, when the mole ratio of Ag3PO4 to Bi2WO6 is 1:2, showed that the photocatalytic activity was the best and the degradation rate can reach more than 98% in 70 min. After 5 cycles of repeated tests, the degradation efficiency of RhB remained at 92% in 90 min and the stability was significantly improved.