Matched Redox Kinetics on Triazine-Based Carbon Nitride/Ni(OH)2 for Stoichiometric Overall Photocatalytic CO2 Conversion.

Mismatched reaction kinetics of CO2 reduction and H2O oxidation is the main obstacle limiting the overall photocatalytic CO2 conversion. Here, a molten salt strategy is used to construct tubular triazine-based carbon nitride (TCN) with more adsorption sites and stronger activation capability. Ni(OH)2 nanosheets are then grown over the TCN to trigger a proton-coupled electron transfer for a stoichiometric overall photocatalytic CO2 conversion via "3CO2 + 2H2O = CH4 + 2CO + 3O2." TCN reduces the energy barrier of H2O dissociation to promote H2O oxidation to O2 and supply sufficient protons to Ni(OH)2, whereby the CO2 conversion is accelerated due to the enhanced proton-coupled electron transfer process enabled by the sufficient proton supply from TCN. This work highlights the importance of matching the reaction kinetics of CO2 reduction and H2O oxidation by proton-coupled electron transfer on stoichiometric overall photocatalytic CO2 conversion.