Protruding‐Shaped Co Polarization Field on Ultrathin Covalent Triazine Framework Nanosheets for Efficient CO2 Photoreduction

Abstract Single‐atom photocatalysts (SAPs) engineered on various supports offer a promising pathway to efficiently convert CO 2 into high‐valued products. However, most SAPs with near‐planar metal atom coordination structure suffer from low conversion efficiency, mainly due to the weak local polarized electric field which retards the reaction kinetics. Herein, this study reports for the first time a photocatalyst which simultaneously integrates protruding‐shaped Co single atom and strong polarization field in ultrathin crystalline covalent‐triazine‐framework nanosheets (donate as Co 1 /CTF‐NSs). Both experimental results and theoretical simulations demonstrated that giant local polarization field is successfully triggered on the Co 1 /CTF‐NSs, which induced directional charge migration and greatly promoted the separation of photogenerated carriers. The protruding‐Co centers enhanced the overlap between CO 2 2p and Co 3d orbitals, thereby facilitating a strong affinity for CO 2 adsorption. Furthermore, the local polarization fields between the protruding‐Co and CO 2 drove the injection of a substantial number of electrons from Co 3d into CO 2 π antibonding orbitals, leading to the effective activation and reduction of the CO 2 molecules. Consequently, the as‐synthesized Co 1 /CTF‐NSs exhibited a remarkable CO production rate of 5391 µmol g −1 h −1 and a high selectivity (97.3%) under visible light irradiation, which represents one of the best molecular framework photocatalysts to date.