Dealloying-Derived Porous Spinel Oxide for Bifunctional Oxygen Electrocatalysis and Rechargeable Zinc-Air Batteries: Promotion of Activity Via Hereditary Al-Doping.

The large-scale fabrication of highly efficient and low-cost bifunctional catalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is critical to the development of rechargeable zinc-air batteries (ZABs). Herein, a scalable dealloying strategy was proposed to obtain hierarchically porous spinel-type oxide with minor hereditary Al doping. Benefiting from the well-structured porosity and native dopant, O-np-Ni 5 Co 10 (Al), namely Al-NiCo 2 O 4 , exhibited excellent electrocatalytic ORR and OER activities, giving a small potential gap of 0.71 V. The rechargeable ZAB with O-np-Ni 5 Co 10 (Al) as cathode catalyst delivered a high specific capacity of 757 mAh g -1 , a competitive peak power density of 142 mW cm -2 , and a long-term discharge-charge cycling stability. Furthermore, density functional theory calculations evidenced that appropriate Al doping into NiCo 2 O 4 could significantly reduce the Gibbs free energy difference to 1.71 eV. This work is expected to inspire the design of performance-oriented bifunctional electrocatalysts for wider applications in renewable energy systems.