Regulating spin configuration of Mn single atoms/Mn atomic clusters catalysts for high-performance zinc-air batteries

Single-atom catalysts exhibit high efficiency and durability in oxygen reduction reactions (ORR). Among the factors influencing ORR activity, the spin configuration of single-atom catalysts can be effectively tuned through heteroatom doping, diatomic synergy, and coordination number regulation. However, systematic investigations into how atomic clusters modulate the spin configuration and catalytic behavior of single atoms in electrocatalysis remain scarce. Herein, Mn atomic clusters are employed to regulate the spin configuration of Mn single atoms, thereby enhancing their intrinsic activity as the primary active sites for high-performance zinc-air batteries. A porous carbon-based two-dimensional (2D) nanosheet (Mn_SA/Mn_AC-NSC) was synthesized, featuring co-existence of Mn atomic clusters and Mn single atoms. The involvement of Mn clusters induces a spin-state transition of Mn single atoms from high-spin to low-spin, which leads to σ* orbital occupation, facilitated OH⁻ desorption, and consequently accelerated reaction kinetics of the rate-determining step. Mn_SA/Mn_AC-NSC exhibited a high half-wave potential (0.85 V) for ORR, surpassing that of the Mn single atom counterpart (Mn-NSC) (0.81 V) and commercial Pt/C (0.75 V). Besides, a zinc-air battery with the Mn_SA/Mn_AC-NSC cathode could deliver a power density of 152.8 mW cm^⁻2 and maintain enduring stability for over 80 h. This work paves the way for designing high-performance single-atom catalysts through cluster-induced spin-state modulation.