Coordination-environment regulation of atomic Co-Mn dual-sites for efficient oxygen reduction reaction

Precisely designing atomic metal-nitrogen-carbon (M-N-C) catalysts with asymmetric diatomic configurations and studying their structure–activity relationships for oxygen reduction reaction (ORR) are important for zinc-air batteries (ZABs). Herein, a dual-atomic-site catalyst (DASC) with CoN3S-MnN2S2 configuration was prepared for the cathodes of ZABs. Compared with Co-N-C (Mn-free) and CoMn-N-C (S-free doping), CoMn-N/S-C exhibits excellent half-wave potential (0.883 V) and turnover frequency (1.54 e·s−1·site−1), surpassing most of the reported state-of-the-art Pt-free ORR catalysts. The CoMn-N/S-C-based ZABs achieve extremely high specific capacity (959 mAh·g−1) and good stability (350 h@5 mA·cm−2). Density functional theory (DFT) calculation shows that the introduction of Mn and S can break the electron configuration symmetry of the original Co 3d orbital, lower the d-band center of the Co site, and optimize the desorption behavior of ⋆OH intermediate, thereby increasing the ORR activity.