Highly Selective Photocatalytic CO₂ Methanation with Water Vapor on Single‐Atom Platinum‐Decorated Defective Carbon Nitride

Solar-driven CO₂ methanation with water is an important route to simultaneously address carbon neutrality and produce fuels. It is challenging to achieve high selectivity in CO₂ methanation due to competing reactions. Nonetheless, aspects of the catalyst design can be controlled with meaningful effects on the catalytic outcomes. We report highly selective CO₂ methanation with water vapor using a photocatalyst that integrates polymeric carbon nitride (CN) with single Pt atoms. As revealed by experimental characterization and theoretical simulations, the widely explored Pt-CN catalyst is adapted for selective CO₂ methanation with our rationally designed synthetic method. The synthesis creates defects in CN along with formation of hydroxyl groups proximal to the coordinated Pt atoms. The photocatalyst exhibits high activity and carbon selectivity (99 %) for CH₄ production in photocatalytic CO₂ reduction with pure water. This work provides atomic scale insight into the design of photocatalysts for selective CO₂ methanation.