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

A simple combustion method was reported to prepare a novel BiOBr: Yb3+, Er3+/AgBr (BYE/AgBr) hetero-junction 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 (similar to 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.