The Preparation,Characterization And Photocatalytic Activity Of Ag₂CrO₄/Ag/BiOI Composites

The traditional p-n junction has the problem that the interface charge transfer efficiency is difficult to coordinate with the redox ability of photo-generated carriers.The Z-scheme photocatalyst can effectively improve the separation efficiency of photogenerated carriers and redox ability.Therefore,in this paper,Ag2CrO4 and BiOI with narrow band gap were selected to construct an All solid-state Z-scheme photocatalyst by photoinduced photolysis,and their structures and properties were characterized and analyzed.On this basis,the microstructure was adjusted by optimizing the synthesis method.The performance of the catalyst in the visible light degradation of Rhodamine B(RhB)and the selective oxidation of benzyl alcohol to benzaldehyde were investigated.The main work and results are as follows:1)Nano Ag microcrystals were formed at the interface of Ag2CrO4 and BiOI by light induction,and the quasi solid-state Z-scheme photocatalyst Ag2CrO4/Ag/BiOI was prepared.The catalyst showed high photocatalytic activity(Degradation:96.03%,6 h)and photo stability in the photocatalytic degradation of RhB.In the selective oxidation of benzyl alcohol,although the conversion of benzyl alcohol was high,the yield of benzaldehyde was low,which indicated the strong oxidation ability of heterojunction photocatalyst.2)Ag2CrO4 and Ag2CrO4/Ag/BiOI heterogeneous photocatalyst were synthesized in water phase,water in oil phase and glycol phase.The effects of loading amount and preparation conditions of Ag2CrO4 on the structure and catalytic performance of the photocatalysts were investigated.The results show that the photocatalysis activity of the Ag2CrO4/Ag/BiOI heterojunction showed better performance when the content of Ag2CrO4 is 40%,in which Ag2CrO4/Ag/BiOI(W/O)prepared in water in oil phase has the best performance.This is due to Ag2CrO4 prepared in water in oil phase has smaller size and highly dispersed on BiOI,which is conducive to the formation of heterojunction,resulting in the improvement of photogenerated carrier separation efficiency.3)Ag/BiOI was first synthesized by direct reduction,photochemical reduction and dye sensitization,further prepared Ag2CrO4/Ag/BiOI heterojunction photocatalyst by in-situ deposition of Ag2CrO4.The effects of the structure of Ag interface prepared by different methods on the performance of heterojunction photocatalysts were investigated.When the Ag content was 1 wt%,U-Ag/BiOI prepared by photochemical reduction showed the highest catalytic activity.Ag2CrO4/U-Ag/BiOI prepared by photochemical reduction showed higher catalytic activity after in-situ deposition of Ag2CrO4.The reason is that the Ag particle size of Ag2CrO4/U-Ag/BiOI prepared by photochemical reduction is smaller and evenly dispersed,which is conducive to the interface charge transfer,thus improving the photocatalytic performance of the catalyst.