Atomically modulated Cu single-atom catalysts for oxygen reduction reactions towards high-power density Zn– and Al–air batteries

Herein, Cu single-atom-encapsulated hollow carbon–nitrogen spheres (CuSA@CNS) are fabricated through a solution process, confining optimal electronic structures reinforcing Cu–N₄ active sites. CuSA@CNS demonstrate a remarkable half-wave potential of 0.95 V, mass activity, and a durability of 5000 cycles. Accordingly, CuSA@CNS present record-high power densities of 371 and 289 mW cm⁻² for Zn– and Al–air batteries. The rechargeable Zn–air battery demonstrates an unprecedented small charge–discharge voltage and stable cycling for harsh operations at 50 mA cm⁻², outperforming Pt/C.