Three-Phase Interface Construction on Hydrophobic Carbonaceous Catalysts for Highly Active and Selective Photocatalytic CO2 Conversion

The ever-increasing concern for adverse climate change has stimulated great research enthusiasm for CO2 conversion. The photocatalytic CO2 reduction reaction (CO2RR) has become one of the promising approaches to converting CO2 into value-added fuels. However, CO2RR suffers from intense competition from the hydrogen evolution reaction (HER) for electrons in aqueous solution due to the limited mass transfer of CO2 in water. In this study, we propose to construct the three-phase interface on the photocatalyst surface by decorating with a hydrophobic carbonaceous cocatalyst to achieve efficient contact of CO2 (gas), catalyst (solid), and water (liquid). The decorated photocatalyst exhibits significantly improved CO2-to-CH4 activity, and the CO2RR selectivity is greatly elevated from 61 to 97%. It is demonstrated that the hydrophobic cocatalyst plays a critical role in regulating the CO2RR performance by increasing the interfacial CO2 concentration. Molecular dynamics simulations further reveal that the hydrophobic microenvironment is constructed by preventing the hydrogen bond formation on the carbonaceous cocatalyst surface. Overall, this study provides a general method to relieve the CO2 mass transfer limit to accelerate the CO2RR in water.