Preparation And Properties Research Of Novel Bi-Based Semiconductor Photocatalyst

People in the 21st century are enjoying the firuits of science and technology,also are faced with the problems of energy and the environment.How to solve the problem of energy shortages and environmental pollution has become a problem to be considered.The development and research of renewable energy is of great significance to solve the problems of energy shortage and environmental pollution.Photocatalysis,as a new technology,has extensive research in addressing energy and environmental issues.In this paper,the bismuth vanadate photocatalyst is studied,and its crystal structure,surface morphology,absorption spectrum and photocatalytic test are studied.The main works are as follows:In the chapter 2,the new photocatalyst BigV2O17 was prepared by Pechini method.The phase of the sample was confirmed by X-ray diffaction.The structure parameters of the samples were characterized by crystal structure refinement,scanning electron microscopy and transmission electron microscopy.The absorbance spectrum was used to measure the absorption range of the sample under visible light,and the band gap width was 1.85 eV.The Bi8V2O17,also had good photocatalytic performance during the actual catalytic degradation.By analyzing the photocatalytic mechanism,it was found that there were V4+ ions in the Bi8V2O17,and V4+ ions reacted with electrons and holes to form V3+and Vs+ respectively,which played an important role in the photocatalytic degradation process,which improved the photocatalytic performance.In the chapter 3,the structure and morphology of Bi4V2O11,were analyzed by X-ray diffraction,scanning electron microscopy and transmission electron microscopy(TEM).It is found that the crystal structure is a monoclinic structure with a typical Aurivillius structure,and its space is composed of[Bi2O2]2+ and(VO3.5?0.5)2-alterrnately composed of oxygen vacancies Molecular chain composition of perovskite structure.Electrons and holes can move rapidly between[Bi2O2]2+ layers,thereby improving the photocatalytic reaction.It was found that the Bi4V2O11 material with oxygen vacancy could efficiently degrade methylene blue under visible light irradiation,and it still maintained stable crystal structure and photocatalytic activity after several catalytic tests.In chapter 4,Bi7VO13 with high photocatalytic activity has good photocatalytic activity.It is found that the Bi7VO 13 is a monoclinic structure by its crystal structure test.The particle size of the samples prepared by the chemical synthesis method-Pechini method is uniform and the dispersibility is good,which satisfies the requirement of photocatalytic particle size.Because the Bi-6s electron pair can hybridize with the O-2p orbit due to the unique electronic structure of Bi ions,shorten the bandgap width,broaden the visible response region,and its unique[Bi2O2]2+ layer The photo-generated electron-hole pairs move so that they have good photocatalytie activity.In the chapter 5,SrBi3VO8 as a new type of photocatalyst material,its photocatalytic performance mainly from its degradation of methylene blue solution to verify.It was found that SrBi3VO8 could degrade methylene blue to 78%under the irradiation of visible light for 3 hours,and its kinetic constant was 0.00194 min-1,which was lower than that of other photocatalysts.Fluorescence test analysis SrBi3VO8 material in the 77K,355nm wavelength excitation has a weak red light phenomenon,the decay time of 0.43?s,15.5?s.Indicating that the photocatalysis and luminescence are antagonistic to some extent,and the photo-generated electron-hole pair is recombined for light emission,thereby reducing the photocatalytic performance.