Synthesis And Photocatalytic Activity Of Bismuth-Based Semiconductor Composites

As one of the most "green" technologies,semiconductor-based photocatalytic technology can make use of solar energy and decompose organic pollutants without secondary pollution.Bismuth-based semiconductor photocatalysts have been demonstrated to echibit superior photocatalytic activities for the degradation of organic pollutants.However,there are still some drawbacks hindering their practical application,such as the unsatisfactory photo-respond range and short photogenerated electron-hole pair lifetime.In this thesis,we focus on preparing bismuth-based composites to enhance their adsorption capacity,enlarge the optical response range,and improve efficient separation of photogenerated electron-hole pairs.The main results are as follows:Plasmonic Ag/AgCl/Bi2O2CO3 composites were prepared by hydrothermal and deposition-photoreduction in the absence of organic capping agents.The Ag/AgCl/Bi2O2CO3 nanocomposites show improved rhodamine B(RhB)or methylene blue(MB)adsorption capacity and photocatalytic activity compared with pure Bi2O2CO3 and Ag/AgCl.The Ag/AgCl/Bi2O2CO3 composite with 20 wt%Ag/AgCl exhibits the highest photocatalytic activity and remains stable after successive visible light photodegradation of RhB.In addition,it also diplays superior visible light photocatalytic activity towards degradation of colorless phenol.The enhanced photocatalytic activity can be attributed to the surface plasmon resonance effect of in situ generated Ag nanoparticles and synergistic effect of Ag/AgCl and Bi2O2CO3.Hierarchical microsphere Bi2MoO6 was synthesized through a facile solvothermal process.Ag/AgBr nanoparticles were deposited on the surface of Bi2MoO6 via a following deposition-photoreduction technique.The Ag/AgBr/Bi2MoO6 photocatalyst exhibits excellent photocatalytic activity under visible light irradiation for degradation of RhB(0.180 min-1),which is higher than the Ag/AgBr(0.071 min-1)and Bi2MoO6(0.008 min-1),respectively.The degradation of MB and colorless phenol further confirmed the broad spectrum photocatalytic degradation abilities of Ag/AgBr/Bi2MoO6.The excellent photocatalytic performance of the photocatalysts can be ascribed to the efficient visible-light utilization efficiency as well as the construction of Z-scheme.