The Chemical Etching Method Was Used To Synthesize Bi ₂ 3 -BiOBr And Bi <2> -BiOBr / RGO And Photocatalytic Performance Study

At present, there are a variety of environmental problems around the world, including water pollution, light pollution, and the governmentt of environmental pollution is becoming more and more important. The photocatalytic reaction has many advantages such as high efficiency, non-toxic, no two pollution etc. The current focus of photocatalysis research include widening the range of light response and enhance photocatalytic activity of semiconductor photocatalystThis disssertation first introduced the the basic principle and application of photocatalytic technology, then reviewed the methods to improve the photocatalytic activity and the current research of bismuth-based photocatalysts. In this thesis, The Bi2O3-BiOBr and Bi2O3-BiOBr/RGO nanocomposite photocatalyst were prepared, and their structure and morphology were also characterizd by XRD, SEM, UV-Vis, TEMå'ŒEDX, at last the photocatalytic properties and possible mechanism were researched. The detailed works were shown as the following:1.In the first part, Bi2O3 was prepared by a simple precipitation reaction and then a series of Bi2O3-BiOBr nanocomposites were synthesized by a simple chemical etching method using HBr as etching agents. The Optimization of synthesis conditions for Bi2O3-BiOBr were HBr/Bi2O3 molar ratio of 0.3, ultrasonic time 60min, HBr concentration 40%, the photocatalytic degradation rate of RhB is reached 99.4% under UV irradiation for 20 min, the photocatalytic reaction rate constants of Bi2O3-BiOBr were 3.71 and 11.8 times of Bi2O3 and BiOBr, respectively. Study on the photocatalytic mechanism shown that superoxide radical (O2O and hole (hvB+) reactive intermediates plays a key role degradation of in the degradation process of RhB with Bi2O3-BiOBr as photocatalyst2.1n the sencond part, a series of Bi2O3-BiOBr/RGO nanocomposites were prepared by a hydrothermal synthesis and simple chemical etching method. The prepared samples were characterized by XRD, SEM, UV-vis,TEM and EDX. The Optimization of synthesis conditions for Bi2O3-BiOBr/RGO were HBr/Bi2O3 molar ratio of 0.5, the content of graphene 2.5%, the photocatalytic degradation rate of RhB is reached 99.5% under UV irradiation for 20 min, the photocatalytic reaction rate constants of Bi2O3-BiOBr/RGO were 1.50,3.71 and 11.8 times of Bi2O3-BiOBr, Bi2O3 and BiOBr, respectively. Research on the photocatalytic mechanism shown that the superoxide radical (O2·-) and hole (hvB+) were the main active intermediate in the process of photocatalytic degradation of RhB when Bi2O3-BiOBr/RGO were usd as photocatalyst.