Spatially confined atomic manganese in N-doped carbon for oxygen reduction in Zn-air batteries

Non-precious Mn-based catalysts have emerged as highly desirable oxygen reduction reaction (ORR) electrocatalysts for Zn-air batteries, as they possess comparable activity to Fe-based catalysts while exhibiting superior stability by avoiding Fenton-induced degradation. Herein, we report an N-doped mesoporous carbon catalyst with atomically dispersed Mn-N_x sites (Mn-NMC), where the spatial confinement effect of its porous NMC architecture (BET surface area: 2161.6 m² g⁻¹) enables effective stabilization and accessibility of single Mn atoms. Therefore, Mn-NMC catalyst achieves exceptional ORR activity and durability through synergistic combination of atomically dispersed Mn-N_x active sites in enhancing intrinsic activity and the porous NMC matrix in optimizing active sites accessibility and mass transport. It delivers a half-wave potential of 0.90 V vs. RHE, a kinetic current density of 46.4 mA cm⁻² at 0.85 V, and 96 % current retention after 6 h of continuous operation, significantly outperforming its conventional NC-based counterparts. In practical applications, the Mn-NMC-based cathodes enable Zn-air batteries to achieve high peak power densities of 178/400 mW cm⁻² (aqueous/flexible), favorable rate capability maintaining stable operation up to 50/40 mA cm⁻², along with satisfactory cycling stability for ∼ 1100/85 h. Apart from that, Mn-NMC-based aqueous Zn-air battery can operate well at -4 °C, delivering a peak power density of 116 mW cm⁻² and maintaining stable operation for over 260 h at 10 mA cm⁻². These results highlight the structural advantages of Mn-NMC as a sustainable alternative to precious-metal catalysts for next-generation energy technologies.