Epoxidized Single-Atom Co-N-C Catalysts Promote the Oxygen Reduction Reaction via a Two-Electron Pathway

Coordination structure and group modifications of single-atom catalysts are essential for regulating superficial electronic structures and reaction activities. Epoxy group-modified single-atom Co-N-C configuration demonstrates exceptional catalytic performance for hydrogen peroxide production. Through the manipulation of the coordination structure of Co-N-C and the doped epoxy groups, we elucidate the origin of catalytic activity in epoxygroup-modified Co-N-C configurations. Theoretical results indicate that the second coordination sphere of the Co-N-C structure is essential for the regulation of the two-electron pathway by the epoxy groups acting as cocatalysts. This cocatalytic mechanism originates from hydrogen bonding interactions between the epoxy groups and the OOH intermediates. Three epoxy groups within the second coordination sphere of Co-N-C configuration lead to the achievement of the optimal G_*OOH (∼4.22 eV) for hydrogen peroxide production. This study offers novel insights into the design of catalytic materials for the electrosynthesis of hydrogen peroxide as well as the engineering of their surface structures.