Gas-solid photoelectrocatalytic CO2 reduction using solid planar photoelectrocatalytic device ITO/RGO/ITO

Photoelectric co-catalysis is a promising method for carbon dioxide (CO2) reduction due to its greater flexibility and higher reaction efficiency. However, the development of gas-phase photoelectrocatalysis is still in progress. Additionally, there is limited information available regarding the intrinsic photocatalytic capability of reduced graphene oxide (RGO) and its "structure-activity" relationship. In this study, solid planar photoelectrocatalytic (PEC) devices ITO/RGO/ITO were designed to enable gas-solid PEC CO2 reduction. The device consists of two strip electrodes functioning as the cathode and anode, biased to create a horizontal electric field that facilitates the separation of photogenerated electron-hole pairs. RGO-130 (heat treatment at 130 °C) presented the best PEC CO2 reduction efficiency, 2.2 times higher than photocatalysis under visible light irradiation. This enhancement can be attributed to its moderate oxygen content (48.8%), 001 crystal face and "layer upon layer" structure, all of which facilitate the separation and transfer of photogenerated carriers. Therefore, RGO is capable of acting as a stand-alone catalyst for the photocatalytic CO2 reduction, and the appropriate design of RGO in surface and structure can improve its activity. This work provides a new perspective on research and application of PEC CO2 reduction, in view of its environmentally safe and conducive to large-scale applications.