Effective photocatalytic salicylic acid removal under visible light irradiation using Ag2S/AgI-Bi2S3/BiOI with Z-scheme heterojunctions

Abstract

A photocatalyst of Ag2S/AgI-Bi2S3/BiOI was synthesized with Z-scheme heterojunctions simply by the S2−-I− anion exchange route showing broad visible light response and enhanced photogenerated carriers properties. The yielded Ag2S/AgI-Bi2S3/BiOI could feature the reactive active sites of Bi2S3/BiOI and Ag2S/AgI heterojunctions, serving as the photogenerated electron donors and photogenerated electron acceptors, respectively. Ag bridges were generated to ensure the construction of Z-scheme strategy, which further improved the migration direction of charge carriers in nanocomposites. Moreover, the analysis of photoluminescence spectra and electrochemical impedance spectroscopy could testified the functions of heterojunctions, which dramatically achieved the enhanced separation and transferring capacity of photogenerated electron-hole pairs in photocatalyst, respectively. In addition, Ag2S/AgI-Bi2S3/BiOI with large specific surface area facilitated the efficient photocatalytic removal of salicylic acid (SA) (up to 89.2%) under visible light. Favorable photocatalytic production of hydrogen peroxide (H2O2) were obtained in pure water driven by the visible light. Besides, by the results of capture experiments, DMPO spin trapping ESR spectra and band structures analysis, the Z-scheme manner of the nanocomposites could promote the reduction ability of photo-generated electrons so as to produce numerous ·O2− during the photocatalytic reactions toward the photocatalytic SA removal and H2O2 production.