Atomic Level Surface Tuning of High-Performance Cobalt Single Atom Electrocatalysts for ORR: From Active Sites to Nanostructures

The development of ORR catalysts with superior performance has entered a paradigm, pivoting from bulk composition toward atomic-level surface tuning of active sites. This review explores the transformative advances in cobalt single-atom catalysts (Co–SACs), emphasizing the critical role of coordination environment engineering, electronic modulation, and morphological control. Particular focus is given to the usage of metal–organic frameworks (MOFs) and covalent organic frameworks (COFs) as versatile precursors for crafting atomically dispersed Co sites with tailored local environments, offering unprecedented control over active site architecture and electronic structure. These frameworks not only facilitate high metal loading and dispersion but also introduce tunable porosity and functional groups that enhance ORR kinetics and stability. The review also examines recent developments in dual-metal synergy, surface/interface engineering, and in situ restructuring strategies that elevate catalytic activity and durability. By integrating experimental insights with theoretical modeling, we provide a unified understanding of how atomic-level design principles rooted in advanced materials chemistry enable next-generation electrocatalysts with superior selectivity and long-term stability for real-world energy systems. Finally, current challenges and future opportunities are critically discussed, offering perspectives for the rational development of MOF/COF-derived Co–SACs for sustainable energy conversion.