Insight into the enhanced photocatalytic properties of AgBr/Ag4P2O7 composites synthesized via in situ ion exchange reaction

Abstract

Photocatalysis is a promising advanced oxidation technology aimed to assist in the degradation of toxic contaminants found in wastewaters into harmless compounds. Here, we report a simple and versatile synthetic route based on in situ ion exchange reaction to produce AgBr/Ag4P2O7 composites with improved photocatalytic performance. All AgBr/Ag4P2O7 composites prepared with different Br/P ratios exhibited superior photocatalytic activities compared to their respective single counterparts. The optimized condition was found at 50 mol%, whose photocatalyst was able to degrade the rhodamine B (RhB) up to 4 min under ultraviolet irradiation. This high photocatalytic performance was maintained even after five successive cycling runs. In the photocatalytic reactions by using AgBr/Ag4P2O7 composites, OH•, Br•, O2•− radicals and photogenerated holes were the main active species responsible for the oxidation of RhB molecules. Our samples presented indirect transitions with band gap energies from 3.20 eV to 3.40 eV, resulting in maximum photoluminescence (PL) emissions within the ultraviolet energy range. Thus, the broadband PL profiles were predominantly controlled by shallow-level defect states in the band gap. These results hold great promise for generating new silver-based materials with enhanced photocatalytic and optical properties.