Preparation And Photocatalytic Properties Of Silver Plasma Enhanced Bi₅O₇I/g-C₃N₄

With the development of the economy and the continuous acceleration of the industrialization process,the problems of energy shortage and environmental pollution are becoming more and more serious.Among them,the most serious water pollution has posed a serious threat to human health,and there are various methods to improve water pollution.The photocatalytic technology with mild reaction conditions and no other harmful substances is widely used.At present,the development of novel photocatalysts with visible light response and stable performance and structure has become a research hotspot.The Bi OX family has some oxygen-enriched structures,i.e.,the number of X atoms is less than the number of O atoms.As one of them,Bi₅O₇I shows great potential for the treatment of organic pollutants.However,the photocatalytic efficiency of Bi₅O₇I is low due to its shortcomings such as easy electron-hole recombination.Since the plasma can effectively inhibit the e^--h⁺recombination,it is beneficial to enhance the photocatalytic efficiency.Therefore,on the basis of the preparation of Bi₅O₇I,Ag nanoparticles were introduced and further combined with g-C₃N₄ to prepare a new photocatalyst Ag/Bi₅O₇I/g-C₃N₄ composite material.The main research contents are as follows:The Bi₅O₇I was prepared by oil bath and calcination,and the Bi₅O₇I/g-C₃N₄composite was preparation by physical agitation.The Bi₅O₇I/g-C₃N₄ composites under different preparation conditions were pure phase,with almost the same phase structure,but the specific surface area differences of the prepared products were obvious.At the same time,the light absorption capacity of photocatalysts prepared under different conditions has no significant difference.The photocatalytic performance test showed that the degradation rate of Bi₅O₇I/g-C₃N₄ composite prepared at 5 wt%g-C₃N₄,25^oC,2h under visible light for 60 min could reach 53%for methyl orange.The Ag/Bi₅O₇I/g-C₃N₄ composites was prepared by photoreduction and physical stirring,and a series of characterization and photocatalytic MO degradation experiments were performed.The study shows that there is no obvious difference in the phase structure of the composites prepared under different conditions,but Ag/Bi₅O₇I/g-C₃N₄composite widened the light response range and increased the specific surface area compared with pure Bi₅O₇I and Bi₅O₇I/g-C₃N₄.The photocatalytic performance test showed that the Ag/Bi₅O₇I/g-C₃N₄ composite prepared with 1 wt%Ag,photoreduction for 1 h,and 5 wt%g-C₃N₄ degradation rate of methyl orange reached 96.4%under 60min of visible light.The active species and stability of the photocatalysts were investigated by trapping and cycling experiments.The results of capture experiment showed that superoxide radical played a major role in the degradation of methyl orange by Ag/Bi₅O₇I/g-C₃N₄composites,while hydroxyl radical and hole played a minor role.The results of cycling experiments showed that the Ag/Bi₅O₇I/g-C₃N₄ composites maintained good stability and efficient photocatalytic performance during 5 cycles.