Exploring the synergistic regulation mechanism of N/C coordination and OH ligands on the bifunctional oxygen electrode activity in Co-N-C doped graphene

Metal–air batteries and proton exchange membrane fuel cells hold great promise for sustainable energy conversion but are limited by sluggish oxygen reduction and evolution reaction kinetics and high noble metal costs. Transition metal–nitrogen–carbon (M−N−C) materials are economical alternatives; however, the effects of specific coordination environments and hydroxyl ligands on Co–N–C catalysts remain underexplored. Herein, we developed 15 Co–N–C doped graphene models featuring four-coordinate, three-coordinate, and hydroxyl-functionalized sites and systematically investigated their bifunctional catalytic performance via density functional theory (DFT). Our results reveal that in four-coordinate configurations, increasing nitrogen content enhances oxygen intermediate adsorption and lowers the overpotential. In three-coordinate systems, CoN 3 and CoN 2 C 1 exhibit low oxygen evolution reaction (OER) overpotentials (0.32 V and 0.30 V, respectively) through an optimized *OOH dissociation pathway. Additionally, hydroxyl ligands markedly improve oxygen reduction reaction (ORR) kinetics, with Co(OH)N 3 achieving an overpotential of 0.41 V as the OH group acts as an “electron storage site” to modulate Co 3d states, balancing O 2 activation and intermediate desorption. These findings offer a new strategy beyond static coordination tuning, highlighting the potential of dynamic ligand engineering in single-atom catalysts. Overall, our study clarifies the link between coordination structure and catalytic performance, paving the way for further advancements in designing efficient, stable non-precious metal electrocatalysts for sustainable energy applications.