Facilitating space charge directional separation for enhancing photocatalytic CO2 reduction over tetragonal BiVO4†
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 MnOx is synthesized by a photo-deposition method for CO2 photoreduction without sacrificial agents. Compared with individual Ag–BiVO4 and MnOx–BiVO4, Ag–MnOx–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–MnOx–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.