Preparation And Research Of Photocatalytic Performance Of AgI/Bi₅O₇I Composite

Photocatalyst can degrade organic pollutants effectively by using sunlight,reducing energy consumption,alleviating the degree of environmental pollution caused by urbanization and industrialization.However,photocatalysis exists such problems as narrow absorption range of visible light,easy recombination and low transmission efficiency of photo-induced carriers,the improvement of photocatalytic performance has reached the bottleneck.Bi₅O₇I is a new-type photocatalyst with excellent stability,positive valence band position,and delocalized valence band top,which can provide more holes to oxidize organic pollutants.In this paper,visible-light responsed Z-scheme AgI/Bi₅O₇I composite materials under mild conditions with excellent photocatalytic activity was prepared.AgI/Bi₅O₇I composite materials were prepared in energy saving and high efficiency method by chemical precipitation transformation and in-situ deposition at room temperature.The photocatalytic properties of AgI/Bi₅O₇I composite materials were studied.The formation mechanism of AgI/Bi₅O₇I composite was further investigated.The absorption edge of sunlight AgI/Bi₅O₇I composite expanded to 667 nm,the recombination of photo-generated carriers was inhibited,and the transmission efficiency of photo-induced carriers was high.AgI/Bi₅O₇I composite was prepared efficiently at room temperature by chemical precipitation transformation in-situ deposition method.Under visible light irradiation???420nm?for 70 min,the photocatalytic degradation rate constant of AgI/Bi₅O₇I composite material toward 10 mg/L MO organic pollutant reached to 0.0518 min^-1,which was 25.9 times than that of pure Bi₅O₇I and 38.4 times than that of pure AgI.The main active species of the photocatalytic reaction were superoxide free radicals and holes.The photocatalytic process of solid Z-scheme AgI/Bi₅O₇I composite has strong redox capacity,high mobility of photo-generated carriers and the exposured?312?crystal surface can improve the photocatalytic effect.The influence relationships between phase composition and morphology of products and preparation condition change of products including NaOH amount,reaction solvent,stirring time as well as surfactant were investigated.The formation mechanism of AgI/Bi₅O₇I composite was discussed.This study provides an effective case toward preparing nanomaterials efficiently at room temperature by chemical precipitation transformation-in situ deposition method,a construction idea of designing semiconductor photocatalyst with controllable morphology by abundant experiments in formation mechanism research,and the effective amplification of stirring method at room temperature can be beneficial to the industrial production of materials in the future.