Enhanced photocatalytic CO2 reduction to methane over WO3·0.33H2O via Mo doping

Abstract

Photocatalytic CO2 reduction is a promising strategy to address environmental and energy issues that are vexing the modern society. However, the efficiency of CO2 photoreduction into fuels such as methane (CH4) is substantially restricted by high CO2 activation barrier and inefficient proton supply. Here, Mo-doped WO3·0.33H2O nanorods have been synthesized and Mo doping in WO3·0.33H2O dramatically increased the CH4 production yield by 5.2 times from 1.02 to 5.3 μmol gcat−1 h−1 under water vapor without the assistant of any sacrificial agent or noble metal. The Mo doping proves capable of facilitating CO2 activation by improving the ability to store and localize photogenerated electrons and boosting the transfer of photoexcited electrons to adsorbed CO2. In addition, proton and electron insertion converts WO3·0.33H2O into tungsten bronze (HxWO3·0.33H2O) under light irradiation, guaranteeing required electrons and protons for CO2 reduction. The enhanced water oxidation of Mo-doped WO3·0.33H2O promotes proton supply and insertion process, improving the hydrogenation process of the carbon intermediate to generate CH4. The combined action of the enhanced CO2 activation and water oxidation with efficient proton and electron insertion improves the performance of CO2 photoreduction to CH4. This work might help to shed light on deeper insights into the design of CO2 photoreduction catalysts.