Engineering the Local Coordination Environment and Density of FeN4 Sites by Mn Cooperation for Electrocatalytic Oxygen Reduction

Abstract Single atom sites (SAS) of FeN 4 are clarified as one of the most active components for the oxygen reduction reaction (ORR). Effective strategies by engineering the local coordination environment and site density of FeN 4 sites are crucial to further enhance the electrocatalytic ORR performance. Herein, the integration of a second metal of Mn with Fe to construct Fe&Mn/N‐C catalysts with enhanced density of FeN 4 active sites and modulated electronic structure is reported. The formation of MnN 4 centers modulates the local environment of FeN 4 sites and reserves more FeN 4 embedded in carbon substrate by forming the possible FeN 4 ‐O‐MnN 4 configurations. Density functional theory calculations demonstrate that the overall energy barrier of ORR is decreased over the FeN 4 ‐O‐MnN 4 moieties. Therefore, the Fe&Mn/N‐C catalyst exhibits enhanced ORR performance both in alkaline and acidic solution (half‐wave potentials are 0.904 and 0.781 V). This work provides an effective strategy by modulating the local electronic structure and density of FeN 4 active sites to improve the ORR activity and stability through Mn cooperation.