Highly-Exposed Co-CoO Derived from Nanosized ZIF-67 on N-Doped Porous Carbon Foam as Efficient Electrocatalyst for Zinc-Air Battery

Non-precious-metal based electrocatalysts with highly-exposed and well-dispersed active sites are crucially needed to achieve superior electrocatalytic performance for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) toward zinc-air battery (ZAB). Herein, Co-CoO heterostructures derived from nanosized ZIF-67 are densely-exposed and strongly-immobilized onto N-doped porous carbon foam (NPCF) through a self-sacrificial pyrolysis strategy. Benefited from the high exposure of Co-CoO heterostructures and the favorable mass and electron transfer ability of NPCF, the Co-CoO/NPCF electrocatalyst exhibits remarkable performance for both ORR (E-1/2 = 0.843 V vs RHE) and OER (Ej = 10 mA cm-2 = 1.586 V vs RHE). Further application of Co-CoO/NPCF as the air-cathode in rechargeable ZAB achieves superior performance for liquid-state ZAB (214.1 mW cm(-2) and 600 cycles) and flexible all-solid-state ZAB (93.1 mW cm(-2) and 140 cycles). Results from DFT calculations demonstrate that the electronic metal-support interactions between Co-CoO and NPCF via abundant C-N-x sites is favorable for electronic structure modulation, accounting for the remarkable performance.

Automated summary

In this study, non-precious-metal based electrocatalysts with highly-exposed and well-dispersed active sites were successfully synthesized. The Co-CoO/NPCF electrocatalyst exhibited remarkable performance for both ORR and OER due to the high exposure of Co-CoO heterostructures and the favorable mass and electron transfer ability of NPCF. Further application of Co-CoO/NPCF in rechargeable ZAB achieved superior performance for liquid-state ZAB and flexible all-solid-state ZAB.