Novel one-step combustion synthesis of BiOBr:Yb3+,Er3+/AgBr upconversion heterojunction photocatalysts with enhanced vis/NIR photocatalytic activities

Abstract

A simple combustion method was reported to prepare a novel BiOBr:Yb³⁺,Er³⁺/AgBr (BYE/AgBr) heterojunction photocatalyst. Phase composition, morphology and optical properties of samples were characterized. The diffuse reflectance and photoluminescence spectra showed that the as-synthesized BYE/AgBr can be activated under both visible (vis) and near-infrared (NIR) light. Notably, BYE/AgBr composites exhibited enhanced photocatalytic activity for RhB degradation under vis/NIR irradiation. The degradation rate constants of BYE/AgBr-1 : 1.5 for RhB were 0.0220 min⁻¹ and 0.01368 h⁻¹ under visible and NIR irradiation, which are about 2.6 and 4.9 times higher than that of pure BYE, respectively. The upconversion effect of Er³⁺ can convert the NIR light (∼980 nm) to visible light which was then absorbed by BYE/AgBr to generate e⁻ and h⁺. Moreover, the formation of the heterojunction also plays a role in the enhanced vis/NIR photocatalytic abilities; and a corresponding plausible photocatalytic mechanism was proposed.