Unveiling the synergistic mechanism of Co-Cu catalysts for efficient oxygen evolution reactions

•Co-Cu catalysts break the limit of conventional AEM sites.•Path II (H2O → *OH → *2OH → *OOH → O2) was identified as the most efficient Co-Cu OER pathway.•The synergistic effect of Co and Cu optimizes the electronic structure and reduces the overpotential. The development of highly active electrocatalysts for Oxygen Evolution Reactions (OER) is critical in the field of energy conversion and storage. Among potential candidates, diatomic catalysts have demonstrated the potential to outperform monoatomic counterparts, though comprehensive studies on their reaction mechanisms remain limited. In this study, a Co-Cu diatomic catalyst was computationally designed using density functional theory (DFT), and four reaction pathways involving multiple intermediates (*O, *OH, *OOH, *2OH, *O + *OH) were calculated. The results indicate that the Co-Cu diatomic catalyst exhibits superior catalytic performance on pathway II (H2O → *OH → *2OH → *OOH → O2) with an overpotential of 0.27 V, overcoming the limitations imposed by the active site of conventional anion exchange membrane (AEM) catalysts. The high catalytic activity is attributed to the synergistic interaction between the metal atoms, bypassing the high-energy barrier step typically observed in conventional pathways. In this mechanism, the Cu d-band center is close to the Fermi energy level, enhancing electron transfer, while Co provides a stable adsorption site and effectively regulates the adsorption and conversion of reaction intermediates. These findings offer new strategies for the rational synthesis of bimetallic catalysts.