Synthesis of MnM–NC (M = Ga, In, Sn) dual-single-atom catalysts for efficient electrocatalytic oxygen reduction

Abstract

The oxygen reduction reaction (ORR) is an important reaction in the field of energy conversion and storage. Manganese-based catalysts are expected to be alternative candidates to iron-based or platinum-group catalysts by virtue of their low cost, good stability and resistance to Fenton reactions. The easily tunable localized p-orbitals of p-block metals and the d-orbitals of manganese can hybridize, which facilitates the oxygen reduction process. Here, we have designed and synthesized a series of dual-single-atom catalysts that consist of Mn and p-block metal single atoms dispersed on N-doped carbon, denoted as MnM–NC (M = Ga/In/Sn). After introducing p-block metal single atoms, the half-wave potential of the catalysts increases to 0.85 V (vs. RHE), and their stability is also improved, even surpassing that of commercial Pt/C. Theoretical calculations show that the dual-single-atom sites could adjust the d-band center of the Mn site, weakening the adsorption strength of the intermediate *OH, thus improving the ORR catalytic activity. This work provides insights into the coupling of Mn–NC species with p-block metals to improve ORR performance and also inspires more structural and application innovations of p-block metals in the ORR research field.