Construction Of Bismuth Vanadate Based Multi-component Composite Catalyst System And Its Visible Light Performance

Energy and environmental issues have attracted global attention.Renewable energy production and environmental protection have become the focus of scientific research.Semiconductor photocatalytic technology is considered to be one of the most promising ways to solve energy shortages and environmental pollution?such as decomposing water into hydrogen and oxygen,photocatalysis for selective organic synthesis and pollutants removal?.In order to utilize this advanced technology better and benefit sustainable development,some scientists have turned to new photocatalysts research.Monoclinic scheelite type bismuth vanadate?BiVO₄?is a visible light response photocatalyst with advantages of low cost,non-toxicity,good stability,and suitable valence band edge? 2.4 eV?.It is significant to promote the semiconductor photocatalytic technology in novel organic pollutants decomposition.However,pure BiVO₄ is difficult to be implemented in removing pollutant due to the defects of easy photocurrent recombination and insufficient visible light utilization.In this research,Bismuth vanadate-based multiple composite catalyst system is constructed through structural design and component adjustment,on the foundation of BiVO₄,to degrade organic pollutants efficiently.The specific innovation results are as follows:?1?A new Ag/Ag₂O/BiVO₄ plasma nano-composite photocatalyst was sythesis by simple precipitation and thermal decomposition methods to enhance photocatalytic activity against drug micro-pollutants.Among a series of materials,Ag/Ag₂O/BiVO₄ nanocomposites show the best performance under 10-minute visible light irradiation under the Ag/Ag₂ O mass ratio of 5% and their photodegradation rate is 6.57 times higher than that of pure BiVO₄.In addition,the effects of different initial pollutant concentrations,catalyst dosage,p H value,and coexisting ions on the photodegradation target pollutant tetracycline hydrochloride?TC-HCl?system were studied.Diverse water sources and cycling experiments were used to explore the feasibility of its practical application.The mechanism studies show that all of photo-generated holes?h⁺?,superoxide radicals??O₂^-?and hydroxyl radicals??OH?participate in the removal of TC-HCl,which is different from the pure BiVO₄ reaction system.This research can provide a new design idea for constructing photocatalysts with high photocatalytic activity.?2?Silver-based materials?Ag/Ag₂O?and graphite-phase carbon nitride?g-C₃N₄?are used to modify BiVO₄ and photodegradable drug micro-pollutants under the light conditions.In this quaternary composite photocatalytic material,Ag/Ag₂ O obviously limits the photo-generated electron-hole pair recombination of BiVO₄ and gC₃N₄/BiVO₄.Compared with pure BiVO₄,g-C₃N₄,g-C₃N₄/BiVO₄ and Ag/Ag₂O/BiVO₄ photocatalysts,Ag/Ag₂O/g-C₃N₄/BiVO₄ exhibits best photocatalytic performance under the best experimental conditions?the initial concentration of pollutants is 10 g/L,the amount of catalyst used is 1 g/L,pH=5?.Electron spin resonance?ESR?results indicate that Ag/Ag₂O/g-C₃N₄/BiVO₄ enhances the separation of photo-generated electrons and holes,and then generates a large number of active groups.The photocatalytic degradation efficiency of TC-HCl was tested by adding a free radical scavenger and ?O₂^-and h⁺ were the main factors in the photocatalytic degradation of TC-HCl.Coexisting ions in tap water and river water reduce the photodegradation efficiency of TC-HCl.The overall results show that the photocatalytic technology has broad application prospects in the degradation of TCHCl.