Preparation And Photocatalytic Performance Of Visible Light-driven Ag/BiVO₄ Photocatalysts

With the rapid development of our society empowered from science and technology,water pollution and environmental damage are becoming more and more serious.Among them,the wanton discharge of chromium-containing wastewater in the industry and the abuse of tetracycline antibiotics are particularly serious,and need to be solved urgently in today’s society.Visble-light photocatalytic process is considered to be a green and efficient treatment technology.In this paper,a simple one-step hydrothermal method was used to synthesize Ag/BiVO₄visible light-driven photocatalytic material,and its structural,morphological and optical electrochemical properties were characterized by XRD,SEM,XPS,EIS techniques.The results of visible light catalytic reduction of Cr（Ⅵ）and photocatalytic degradation of tetracycline hydrochloride showed that the introduction of Ag could significantly improve the photocatalytic performance of BiVO₄.1.For the photocatalytic reduction of Cr（Ⅵ）,Ag/BiVO₄with the atomic ratio of Ag:Bi=1:20,noted as Ag-B20,has the best activity:while the reduction ratio of Cr（Ⅵ）on pristine BiVO₄is 53.5%,Ag-B20gives the reduction ratio of 99.3%;the photocatalytic rate constant of Cr（Ⅵ）reduction over pure BiVO₄is 0.0071 min^-1,the rate constant over Ag-B20 can be increased by more than 6 times;after 4 cycles of experiments,the Cr（Ⅵ）reduction efficiency of Ag-B20 can still retain73.0%.2.In the experiment of photocatalytic degradation of tetracycline hydrochloride,the effects of different initial concentrations,catalyst dosage,solution p H and other conditions on the experiment were studied.The experimental results show that Ag/BiVO₄with the atomic ratio of Ag:Bi=1:15,Ag-B15,has the best degradation activity,and its rate constant of photocatalytic degradation of tetracycline hydrochloride is 2.5times that of pure BiVO₄.The p H value of the solution has a significant effect on the photocatalytic degradation of tetracycline hydrochloride.The compsite Ag-B15 shows more excellent photocatalytic performance in a weak alkaline environment.Reactive species capturing experiments were designed to explore the active species in photocatalytic degradation of tetracycline hydrochloride over Ag/BiVO₄.The results state that·O₂^-is the main active specie for the photocatalytic degradation of tetracycline.3.The results of photocurrent analysis and electrochemical AC impedance measurement show that the introduction of Ag can effectively reduce the electrochemical impedance of BiVO₄material,which is beneficial to the space charge separation of photogenerated carriers,thereby improving its photocatalytic performance.