Oxygen Vacancy-Rich In-Doped CoO/CoP Heterostructure as an Effective Air Cathode for Rechargeable Zn-Air Batteries

An efficient and low-cost electrocatalyst for reversible oxygen electrocatalysis is crucial for improving the performance of rechargeable metal-air batteries. Herein, a novel oxygen vacancy-rich 2D porous In-doped CoO/CoP heterostructure (In-CoO/CoP FNS) is designed and developed by a facile free radicals-induced strategy as an effective bifunctional electrocatalyst for rechargeable Zn-air batteries. The electron spin resonance and X-ray absorption near edge spectroscopy provide clear evidence that abundant oxygen vacancies are formed in the interface of In-CoO/CoP FNS. Owing to abundant oxygen vacancies, porous heterostructure, and multiple components, In-CoO/CoP FNS exhibits excellent oxygen reduction reaction activity with a positive half-wave potential of 0.81 V and superior oxygen evolution reaction activity with a low overpotential of 365 mV at 10 mA cm^-2 . Moreover, a home-made Zn-air battery with In-CoO/CoP FNS as an air cathode delivers a large power density of 139.4 mW cm^-2 , a high energy density of 938 Wh kg_Zn ^-1 , and can be steadily cycled over 130 h at 10 mA cm^-2 , demonstrating great application potential in rechargeable metal-air batteries.