Single-Atom Ni Sites with Asymmetric Coordination Structures for Efficient Photocatalytic CO 2 Reduction

The exploration of single-atom catalysts (SACs) with unique coordination structures is of vital importance for boosting photocatalytic CO 2 reduction, yet it remains challenging. Herein, we develop a novel SAC with a unique asymmetric coordination structure of the Ni catalytic site, which can trap photogenerated electrons to realize highly efficient photocatalytic CO 2 reduction in the presence of triethanolamine as an electron donor. Doping a B heteroatom into the N-doped carbon substrate would introduce B–N bond and meanwhile create defects, thus providing a feasible strategy to break the symmetry of the Ni–N 4 moiety and finally producing a coordination unsaturated Ni–N 3 –B structure. It is demonstrated that the asymmetric Ni–N 3 –B species can improve the electron trapping ability and reduce the formation energy barrier of the * COOH intermediate compared with the symmetric Ni–N 4 species for boosting photocatalytic CO 2 reduction. Such a concept of breaking the symmetric coordination structure of SACs could provide a promising approach for constructing effective catalytic sites toward solar energy-driven conversion.