Fabrication of copper-cobalt heterostructures confined inside N-doped carbon nanocages for long-lasting Zn-air batteries

Delicate construction of sophisticated bimetallic nanostructures provides a favorable way to boost the efficiency of bifunctional electrocatalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), which is critical to the fabrication of rechargeable Zn-air batteries. Herein, hetero-structured Cu/Co 93 Cu 7 nanoparticles confined inside N-doped carbon nanocages (denoted as Cu/Co 93 Cu 7 @NC NCs) are fabricated through a facile “MOF-in situ-reduction and in situ-growth-MOF” strategy. Benefiting from the unique hollow architecture and superior intrinsic activity of the optimized interfaces, the as-prepared catalyst displays an appealing electrocatalytic performance including a positive half-wave potential (E 1/2 ) of 0.88 V for ORR and a low OER overpotential of 262 mV at 10 mA cm −2 . Theoretical calculations further disclose the key role of the rationally designed Co/Cu/N-doped carbon heterostructures, which significantly reduces the energy barrier for *OOH formation and eventually promotes the ORR. Rechargeable Zn-air batteries assembled with the Cu/Co 93 Cu 7 @NC NCs exhibit a large specific capacity of 884.9 mAh g Zn −1 and a maximum power density of 225.9 mW cm −2 . Moreover, the assembled batteries are stable for 1000 h during the long-term charge and discharge cycling, demonstrating the great promise for practical applications. • An efficient Cu/Co 93 Cu 7 @NC NCs catalyst is designed for ORR and OER. • The hollow architecture enhances the electrocatalytic kinetics. • DFT verifies that N–C, Cu and Co cooperatively improve the intrinsic activity. • The as-assembled Zn-air batteries exhibit excellent activity and durability.