Breaking the O2 Activation Bottleneck via Synergistic Electronic Polarization at Adjacent Co-Mn Sites in N-Doped Carbon.

Metal-nitrogen-carbon (M-N-C) catalysts with atomically dispersed metal sites have emerged as attractive non-precious alternatives to Pt/C for the oxygen reduction reaction (ORR). Among them, Co-N-C systems have received particular attention because of their favorable stability and low cost, yet isolated Co sites often exhibit insufficient O2 adsorption and charge polarization, limiting further activity enhancement. In this study, we introduce Mn into a Co-N-C matrix via a confined adsorption approach to create adjacent Co-Mn sites. The presence of adjacent Mn electronically modulates the Co center, resulting in a CoMnNC catalyst with markedly improved ORR performance. The catalyst delivers half-wave potential (E1/2) values of 0.80 V in 0.1 M HClO4 and 0.919 V in 0.1 M KOH. Under Zn-air battery testing, its maximum power density reached 193.5 mW cm-2, outperforming Pt/C under identical conditions. Density functional theory (DFT) calculations indicate Mn proximity enriches the electron density at Co and downshifts the Co d-band center. This electronic modulation enhances O2 adsorption and charge polarization, weakens the adsorbed O─O bond and lowers the barrier for OOH* formation. This work clarifies how neighboring metal sites regulate the electronic structure of Co centers to facilitate O2 activation and offers a reference for designing excellent M-N-C catalysts.