| With the development of industrialization,the continuous discharge of industrial wastewater and energy shortage have affected the sustainable development of human beings.Photocatalysts have the potential to convert solar energy into hydrogen and decompose organic pollutants,in which bismuth vanadate（BiVO4）has attracted much attention in the research of photocatalytic materials due to its narrow band gap（2.4 e V）and low-cost.However,it has been found that BiVO4 has disadvantages such as easy compounding of photogenerated carriers and low photocatalytic efficiency.To solve the above problems,this thesis firstly obtained structurally stable tubular BiVO4 by adjusting the pH value of the precursor solution and then studied the effect of Fe doping on the photocatalytic performance of BiVO4 based on tubular BiVO4,the main research is as follows:Monoclinic phase BiVO4（m-BiVO4）photocatalysts with different morphologies were prepared by the hydrothermal method under different pH conditions,in which BiVO4 samples with pH=9 of precursor solution exhibited tubular morphology.The effects of different pH conditions on the structure and properties of BiVO4 were also investigated.The experimental results show that BiVO4 with precursor solution pH=9 has a higher charge separation ability and effectively increases the electron in the valence band to the conduction band migration,resulting in a significant increase in its carrier concentration.The tubular BiVO4 obtained at pH=9 of the precursor solution shows higher photocatalytic activity than the other samples,and its improved photocatalytic performance was mainly attributed to the tubular morphology,larger specific surface area,and stronger light absorption.To investigate the effect of Fe doping on the structure and photocatalytic performance of BiVO4,a series of m-BiVO4 tubular structured photocatalysts with different Fe doping amounts were prepared by ionic substitution method using BiVO4 at pH=9 as the substrate.Density functional theory calculations showed that the Fe doping substituted the V site and the structure of the obtained BiVO4 was stable.The light absorption range and carrier complexation ability of the materials were investigated by UV-vis diffuse reflectance and photoluminescence spectroscopy.The results show that Fe doping can effectively improve light absorption and inhibit the complexation of electron-hole pairs of BiVO4.The sample with Fe doping of 0.1 wt%exhibits the best photocatalytic performance with 1.9 times the primary kinetic rate constant and 1.4 times the hydrogen production rate than that of pure BiVO4.Therefore,the appropriate amount of Fe doping in place of V can have the effect of improving photocatalytic performance.This is because Fe doping induces a local change in the chemical state of the element,which generates new electron/orbital Coulomb interactions and promotes carrier transport and separation. |
