A conjugated composite of α-Fe2O3 and BiOBr with enhanced visible-light-induced photocatalytic activity

Abstract

Owing to its nontoxic property, low cost and narrow band gap, alpha-iron(III) oxide (α-Fe2O3) is a promising material as photocatalyst. However, it has shortcomings such as quick recombination and a short lifetime of the electron-hole pairs, which directly reduce the photocatalytic efficiency of α-Fe2O3 and hinder its wide applications. In this study, a facile hydrothermal method was used to incorporate BiOBr with α-Fe2O3 in an attempt to overcome the previously mentioned limitations of α-Fe2O3, and the synthesized composites were fully characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and UV–vis diffuse-reflection spectroscopy (DRS). The BiOBr/α-Fe2O3 composite showed much higher visible-light-driven photocatalytic activity than the pure α-Fe2O3 and BiOBr for Rhodamine B (RhB) degradation. Specifically, the composite synthesized at 100°C for 18h with a mass ratio of BiOBr to α-Fe2O3 5:10 performed the best. This work also explored the chemical mechanism and pathway of RhB degradation, and the roles of the oxidative species with the presence of BiOBr/α-Fe2O3 composites in the photocatalytic oxidation process, including holes (h+), hydroxyl radicals (OH), and superoxide radicals (O2−).