Local chemical environment effect in single-atom catalysis

Single-atom catalysts (SACs), bridging homogeneous and heterogeneous catalysis, have recently drawn tremendous attention owing to maximized atom utilization, well-defined structures, and unique catalytic performance. While the metal atom (M1) in SACs does not necessarily catalyze reactions alone, the local chemical environments of M1 often jointly drive reactions and shape their catalytic performance. In this review, we discuss the atomic-level understanding of the relations between the coordination environment and the catalytic performance. The role of the coordination structure is emphasized in how M1 atoms and the coordination atoms cooperatively prompt the activation of reactants and key intermediates in oxidation, hydrogenation, and electrocatalytic reactions. Next, we summarize the recent advances in the tailoring of coordination structures and metal-support interactions for catalytic performance optimization in terms of activity, selectivity, and stability. Finally, we discuss the challenges and opportunities in the synthesis of SACs with highly uniform coordination structures for advanced catalysis.