Coordination-environment regulation of atomic Co-Mn dual-sites for efficient oxygen reduction reaction
Caiting Sun, Yarong Liu, Zunhang Lv, Rui Liu, Changli Wang, Liuhua Li, Jinming Wang, Yu Zhang, Wenxiu Yang, Bo Wang
Abstract
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.