Asymmetrical Degree Engineered Carbon Dioxide Photoreduction for Single Atomic Co Sites on Polymeric Carbon Nitride

Asymmetrical coordination engineering of the active moieties, crucial for optimizing the adsorption/desorption of intermediates, enables to enhance the catalytic performance of single‐atom catalysts (SACs) for CO2 photoreduction. However, a universal design concept to synthesize SACs with well‐dispersed asymmetrical coordinated active metal sites is still under discussion. In addition, the regulation mechanism of the asymmetrical configuration of the active metal sites as well as the correlation establishment between the coordination asymmetry and CO2 photoreduction activity of SACs remain have not been demonstrated. Herein, a universal marginal heteroatom doping strategy is developed to synthesize a series of Co SACs for CO2 photoreduction by imbedding various asymmetrical Co coordination sites (CoN4 + B, CoN4 + P, CoN4 + S, and CoN4 + C) in polymeric carbon nitride (g‐C3N4) and a concept of “asymmetrical degree” is introduced to conduct quantitative analysis of these asymmetrical Co coordination sites. The experiments combined with theoretical calculations not only definitely correlate the asymmetrical degree of Co coordination configurations with catalytic activity but also attribute the best CO2 photoreduction activity of single CoN4 + B site catalyst with the highest asymmetrical degree to its substantiated density of states of Co 3d orbital near the Fermi level as well as optimized *CO formation and desorption.