Regulation of excitons dissociation in AgI/Bi3O4Br for advanced reactive oxygen species generation towards photodegradation

Abstract

The electron-hole-mediated exciton effect in two-dimensional materials plays a vital role in the process of photocatalytic reactive oxygen species (ROS) generation. In photocatalytic degradation, the existence of competitive excitons is an important factor limiting the generation of free charge carriers. Herein, a binary nanohybrid of single-unit-cell Bi3O4Br and AgI nanoparticle was designed and used as a photocatalyst for ROS generation. We explored the role of excitons and hot carriers in the photo-induced process through the AgI/Bi3O4Br model, and proved that the exciton dissociation mediated by heterojunction is beneficial to the path of charge transfer in photocatalysis. The extremely high generation efficiency of •OH and O2− is attributed to the reduction of spin-orbit coupling (SOC) in AgI/Bi3O4Br heterojunction and the existence of oxygen vacancies to promote exciton dissociation. Owing to the interfacial interaction between AgI and Bi3O4Br, the generation of 1O2 during the exciton energy transfer process is reduced and further increases the generation of O2− and •OH radicals in the charge transfer path. Benefiting from the enhanced ROS generation, the AgI/Bi3O4Br shows high effective degradation of rhodamine B (RhB), phenol, acetaminophen (APAP) and ciprofloxacin (CIP). This work offers a new strategy to optimize photocatalytic ROS generation for removal of organic pollutants in wastewater.