Coordination Environment Engineering of Fe–N–C Single-Atom Catalysts Toward Oxygen Reduction Reaction

Replacing expensive platinum-based electrocatalysts with low-cost, durable and high-performance alternatives for the oxygen reduction reaction (ORR) is a significant research focus in the fields of sustainable energy and electrocatalysis. Fe─N─C single-atom catalysts have emerged as highly hopeful candidates because of their excellent catalytic activity and stability in oxygen reduction reactions as well as maximized atom utilization efficiency. Recent research progress has highlighted the multi-dimensional and efficient strategies for optimizing the Fe─N─C single-atom catalysts, including coordination nitrogen management, heteroatom doping, bimetallic site design, defect engineering, spin state regulation, axial coordination, metal cluster and nanoparticle integration. These methods can precisely tune coordination environment of Fe active centers, optimize adsorption/desorption energy of ORR intermediates, and improve overall catalytic performance. This review systematically summarizes the latest research achievements of Fe─N─C single-atom catalysts, clarifies the mechanisms of various control strategies, and discusses future development directions. It hopes to provide valuable insights for developing next-generation non-precious metal ORR electrocatalysts and guide their applications in renewable energy technologies.