Engineering the electronic structures of hetero-diatomic iron-manganese sites by d-d orbital hybridization for boosting oxygen reduction

The catalytic performance of metal single-atom catalysts (SACs) can be further improved through d-d orbital hybridization with adjacent metal sites. However, the construction of metal diatomic catalysts (DACs) remains a great challenge, particularly for heteronuclear DACs. Herein, a heteronuclear DACs with Fe and Mn bimetallic sites embedded on a hollow N-doped carbon nanosphere (HNCS) is successfully achieved through a well-designed two-step anchoring and adsorption method. The obtained Fe/Mn-HNCS catalyst exhibits excellent performance for oxygen reduction reaction (ORR) with a half-wave potential of 0.895 V compared to the single Fe and Mn counterparts. Theoretical calculations reveal that d-d orbital hybridization between Fe-Mn diatomic pair causes a fast electron transfer, optimizes their electronic structures, and reduces the energy barriers for *OH desorption, thereby improving the ORR performance. Our results highlight a simple strategy to synthesize heteronuclear DACs and provide new insights into how diatomic metal sites affect electrocatalytic performance.