AgBr nanoparticle surface modified SnO2 enhanced visible light catalytic performance: characterization, mechanism and kinetics study

Abstract

In this study, a simple hydrothermal procedure and in situ precipitation method were used to prepare SnO₂–AgBr composites, where the molar ratios of SnO₂ and AgBr were 1 : 1, 1 : 2 and 2 : 1. Characterization results showed that the composites had excellent dispersion, crystallinity, and purity. A photocatalytic degradation experiment and first-order kinetic model indicate that SnO₂–AgBr (1 : 1) had the best photocatalytic performance, and the degradation rates of 30 mg L⁻¹ simulated MO and MG wastewater reached 96.71% and 93.36%, respectively, in 150 min, which were 3.5 times those of SnO₂. The degradation rate of MO and MG increases with the dosage. Humic acid inhibited the degradation of MG, while a low concentration of humic acid promoted the degradation of MO, and the composite has good stability with pH. A free radical trapping experiment shows that ·OH and ·O₂⁻ were the main active substances, and h⁺ was the secondary one. According to the results of the characterization and photocatalysis experiments, a Z-scheme mechanism for the SnO₂–AgBr composite was proposed, and the degradation pathway of target pollutants was speculated upon. This study has conceived novel methods for the development of a mature Z-scheme mechanism and in doing so has provided new approaches for the development of photocatalysis for water pollution control.