Mn nanoclusters stabilizing asymmetric single-atomic MnN3 and modulating electronic structure in a dual-site catalyst for high-performance rechargeable zinc-air batteries

Constructing stable and highly active asymmetric Mn N 3 single-atomic sites integrated with Mn nanoclusters remains challenging. This work develops a facile secondary pyrolysis strategy to fabricate a porous dual-site catalyst (Mn SA /Mn NC -NC) featuring both single-atom Mn N 3 (Mn SA ) and Mn nanoclusters (Mn NC ) sites on nitrogen doped carbon black (NC). The Mn NC not only stabilizes the Mn SA but also enhances the overall conductivity and preserves the hierarchical porous framework, thereby maximizes dual-site exposure and mass transport. This synergy endows Mn SA /Mn NC -NC with outstanding activity for bifunctional oxygen catalysis with half-wave potential of 0.91 V and onset potential of 1.59 V, both surpassing those of commercial noble metal Pt/C and RuO 2 . A liquid zinc-air battery (LZAB) assembled with Mn SA /Mn NC -NC achieves a high power density of 218.0 mW cm −2 and stability exceeding 500 h. Density functional theory (DFT) calculations insightfully reveal the inherent mechanism that Mn NC not only stabilizes asymmetric Mn SA , but also precisely modulates the electronic structure and d-band energy levels, which kinetically optimizes the desorption behavior of reaction intermediates *OH and thermodynamically lowers the reaction energy barrier. This work verifies the critical role of nanoclusters on asymmetric single-atom sites, offering essential guidance to design of high performance catalysts for energy storage devices.