In-situ growth of CoNi bimetal on double-walled hollow carbon spheres/ nanotube hybrid for boosting rechargeable Zn-air battery

Non-precious metal catalysts with efficient bifunctional catalytic performance are urgently needed in rechargeable Zn-air battery. Herein, a 3D N-doped double-walled hollow carbon spheres/nanotube CoNi alloy hybrid (CoNi-NC/DLHCs) was rationally constructed by the optimized Sto<spacing diaeresis>ber method combined with the epitaxial attachment MOF strategy. Take advantage of effectively utilized the active site of 3D open architecture, accelerated intermediate transport, and the large specific surface area (SBET), CoNi alloys exerted maximum oxygen reduction reaction (ORR) activity and oxygen evolution reaction (OER) activity. The as-prepared CoNi-NC/DLHCs catalyst manifests a higher half-wave potential of 0.85 V and Tafel slop of 88 mV dec-1 for ORR, as well as satisfied OER activity with Tafel slope of 92 mV dec-1 and overpotential at 10 mA cm-2 of 275 mV. A liquid zinc-air battery equips with CoNi-NC/DLHCs achieved a satisfying open circuit potential (OCP) of 1.51 V, a maximum peak power density of 183.4 mW cm-2, and a cycle endurance stability of more than 700 h. This research highlights good prospects in designing oxygen electrocatalysts catalysts in the metal-air battery field.