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.