Descriptor-Based Design Principle for Two-Dimensional Single-Atom Catalysts: Carbon Dioxide Electroreduction

Single-atom catalysis has recently emerged as a promising approach for catalyzing the carbon dioxide reduction reaction (CO₂RR). In this study, we present a principle for designing active single-atom catalysts (SACs) for CO₂RR. We systematically examine totally 24 transition metals supported by a graphitic carbon nitride (g-CN) monolayer and find that their catalytic activities are highly correlated with the adsorption free energies of two intermediate species (OH and OCH). We then identify two important intrinsic descriptors, namely, the number of electrons in the outmost d-shell and the enthalpy of vaporization of the transition metal. Test calculations on transition metals supported by a C₂N monolayer indicate that both descriptors are quite universal for SACs of CO₂RR. Based on these results, we show that Ni@g-CN, Cu@g-CN, and Co@C₂N are promising SACs for CO₂RR. This study offers an effective principle for designing highly active SACs for CO₂RR on the basis of intrinsic properties of transition metals.