Tuning the atomic configuration environment of MnN4 sites by Co cooperation for efficient oxygen reduction

Carbon-based N-coordinated Mn (Mn-Nx/C) single-atom electrocatalysts are considered as one of the most desirable non-precious oxygen reduction reaction (ORR) candidates due to their insignificant Fenton reactivity, high abundance, and intriguing electrocatalytic performance. However, current Mn-Nx/C single-atom electrocatalysts suffer from high overpotentials because of their low intrinsic activity and unsatisfactory chemical stability. Herein, through an in-situ polymerization-assisted pyrolysis, the Co as a second metal is introduced into the Mn-Nx/C system to construct Co, Mn-Nx dual-metallic sites, which atomically disperse in N-doped 1D carbon nanorods, denoted as Co, Mn-N/CNR and hereafter. Using electron microscopy and X-ray absorption spectroscopy (XAS) techniques, we verify the uniform dispersion of CoN4 and MnN4 atomic sites and confirm the effect of Co doping on the MnN4 electronic structure. Density functional theory (DFT) calculations further elucidate that the energy barrier of rate-determining step (*OH desorption) decreases over the 2 N-bridged MnCoN6 moieties related to the pure MnN4. This work provides an effective strategy to modulate the local coordination environment and elec-tronic structure of MnN4 active sites for improving their ORR activity and stability.(c) 2023 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by ELSEVIER B.V. and Science Press. All rights reserved.

Automated summary

Mn-Nx/C single-atom electrocatalysts have attracted much attention due to their non-precious nature, high abundance, and excellent electrocatalytic performance. However, the high overpotentials are the major challenge for these catalysts. In this study, we introduced Co as a second metal into the Mn-Nx/C system to create Co, Mn-Nx dual-metallic sites, which improved the catalytic activity and stability of the MnN4 active sites.