Facilitating space charge directional separation for enhancing photocatalytic CO2 reduction over tetragonal BiVO4

Abstract

The surface modification of dual cocatalysts on a photocatalyst is believed to effectively promote the separation of photogenerated carriers in the CO₂ reduction reaction. Here, taking tetragonal BiVO₄ with a strain effect as a substrate photocatalyst which has been proven to have enhanced reduction ability, BiVO₄ modified with spatially separated dual cocatalysts Ag and MnO_x is synthesized by a photo-deposition method for CO₂ photoreduction without sacrificial agents. Compared with individual Ag–BiVO₄ and MnO_x–BiVO₄, Ag–MnO_x–BiVO₄ has improved activity for reduction of CO₂ to CO in a gas–solid system, which can be attributed to the spatially separated redox sites and enhanced photogenerated carrier separation efficiency. The optimal activity of the Ag–MnO_x–BiVO₄ sample is 3.1 times that of the original BiVO₄. In addition, PL and photoelectrochemical tests indicate that the dual cocatalysts can effectively inhibit carrier recombination and promote the photocatalytic reaction. This work reports a useful strategy for constructing a photocatalytic CO₂ reduction system based on a BiVO₄ photocatalyst.