Hollow mesoporous metal-nitrogen-carbon electrocatalysts with enhanced oxygen reduction activity for zinc-air...

While great advances have been achieved in Zn-air batteries, porous cathode catalysts remain crucial and challenging to promote diffusion and boost oxygen reduction reaction (ORR). Herein, an effective strategy has been developed for the synthesis of hollow metal-nitrogen-carbon electrocatalysts to achieve the macro-/meso-/microporous structure. The h-CuNC electrocatalyst exhibits good stability and high ORR activity with a half-wave potential of 0.91 V. Theoretical calculations reveal that CuNC sites can reduce the energy barrier of *OOH adsorption, which is the rate-determining step. Zn-air battery with h-CuNC as the cathode catalyst enables high peak power density of 201 mW cm^-2 and good rate performance. Our work demonstrates the concept that hollow mesoporous MNC can significantly improve the catalytic performance by enhancing diffusion.