ZIF-67 as Continuous Self-Sacrifice Template Derived NiCo2O4/Co,N-CNTs Nanocages as Efficient Bifunctional Electrocatalysts for Rechargeable Zn-Air Batteries

Probing competent bifunctional electrocatalysts for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) plays a crucial role in the development of energy conversion and storage systems. Herein, we introduce a continuous self-sacrifice template strategy for synthesis of the novel NiCo2O4/Co,N-CNTs nanocages (NCs) as an efficient ORR/OER bifunctional electrocatalyst for Zn-air batteries. The NiCo2O4 and Co,N-CNTs are derived from the external and internal self-sacrifice of ZIF-67, respectively. The as-prepared NiCo2O4/Co,N-CNTs NCs display remarkable electrocatalytic activity toward ORR. (E-1/2 = 0.862 V) and OER (E-j10 = 1.569 V) simultaneously, outperforming the commercial catalysts like Pt/C and RuO2, respectively. The reversible oxygen electrode index (Delta E = E-j10 (OER) - E-1/2 (ORR)) is similar to 0.707 V in alkaline electrolyte. Interestingly, NiCo2O4/Co,N-CNTs NCs act as a cathode electrocatalyst in a primary Zn-air battery system with a high power density of 173.7 mW cm(-2). Therefore, the continuous self-sacrifice template strategy proposed in this work is expected to inspire the design of high-performance bifunctional nonprecious electrocatalysts for application in sustainable energy conversion devices.