| With the rapid development of society,the pollution of human living environment and natural ecological environment is becoming more and more serious and not optimistic.As a new technology,semiconductor photocatalysis technology has a wide application value in solving the problem of environmental pollution.Among many new photocatalysts,bismuth semiconductor materials stand out in the field of semiconductor photocatalysis because of their special structure and high degradation efficiency.This paper mainly introduces the development of photocatalytic technology,the principle of photocatalytic reaction,the types of bismuth series photocatalytic materials and the improvement methods of bismuth series photocatalytic performance,etc.In order to improve the photocatalytic performance of BiOCl,the following two aspects of work are carried out:（1）First,the simplest hydrothermal method was adopted to prepare BiOCl nanosheets with bismuth nitrate pentahydrate and potassium chloride as raw materials and water as solvent.BiOCl/BiVO4composite heterojunction photocatalyst was prepared by using BiOCl nanosheets as precursors,adding ammonium metavanadate and secondary hydrothermal process to make bismuth vanadate grow closely and uniformly on BiOCl nanosheets.The catalysts were characterized by X-ray diffraction（XRD）,scanning electron microscopy（SEM）,transmission electron microscopy（TEM）and UV-vis diffuse reflectance spectroscopy（UV-Vis）.In this experiment,rhodamine B（Rh B）is the dye to be degraded.The photocatalytic performance of rhodamine solution is evaluated by the degradation effect of composite materials.The experimental results show that BiOCl/BiVO4 composite photocatalytic material has higher photocatalytic activity compared with BiOCl and BiVO4 alone.After four photocatalytic cycle experiments,BiOCl/BiVO4 photocatalytic material still has good photocatalytic activity.This is because the two kinds of semiconductor BiOCl and BiVO4 formed a heterojunction through composite,which promoted the directional movement of electrons in BiOCl/BiVO4 composites,inhibited the composite of photogenerated electron-hole pairs,and finally improved the photocatalytic performance of BiOCl/BiVO4 composites.（2）Using hydrothermal method,with water as solvent,bismuth nitrate pentahydrate,potassium chloride and sodium fluoride as raw materials,the F ion doped BiOCl nanosheets were prepared.The photocatalytic material F/BiOCl/BiVO4 was closely and uniformly grown on F/BiOCl nanosheets by secondary hydrothermal method using F/BiOCl as the precursor and adding ammonium metavanadate.The catalysts were characterized by X-ray diffraction（XRD）,scanning electron microscopy（SEM）and UV-Vis diffuse reflection spectroscopy（UV-Vis）.The performance of the photocatalyst was evaluated with methyl orange as the dye to be degraded.According to the experimental results,F/BiOCl/BiVO4 composite photocatalyst has a higher photocatalytic efficiency than single BiOCl,BiVO4 and F/BiOCl.After four cycles of experiments,the photocatalytic activity of F/BiOCl/BiVO4 composites did not decrease significantly.This may be because the doping of F ion changes the crystal structure of the catalyst itself,enlarges the photoresponse range of BiOCl,and also changes the dipole moment of the material,so as to realize the rapid separation of photogenerated carriers,promote the directional movement of photogenerated carriers,and improve the photocatalytic performance of the material. |
