Multi-component nanoporous alloy/(oxy)hydroxide for bifunctional oxygen electrocatalysis and rechargeable Zn-air batteries

Multi-component high-entropy alloys (HEAs) and their corresponding high-entropy oxides (HEOs) provide great flexibility in modulating the electronic properties and catalytic activities due to the interaction of five or more different metal species. Herein, a top-down dealloying strategy is used to fabricate various noble-metal-free nanoprous HEAs covered with naturally oxidized multi-component surface oxides (HEOs). By tuning the compositions of these nanostructured HEA/HEOs, a bifunctional AlFeCoNiCr oxygen electrocatalyst is discovered. When used in aqueous Zn-air batteries, it delivers an open-circuit potential of 1.55 V, and a high specific capacity of ∼800 mA h g⁻¹. When assembled in solid-state Zn-air batteries, it exhibits a small discharge/charge potential gap of 0.76 V at 2 mA cm^-2 and can be stably cycled for 60 h. Higher performance electrocatalysts are potentially available by exploring a larger design space of the HEA/HEO system.