Enhanced Stability and Narrowed D‐Band Gap of Ce‐Doped Co3O4for Rechargeable Aqueous Zn‐Air Battery

Abstract It remains challenging to achieve further breakthroughs in the development of durable bifunctional air cathode electrocatalysts for increasing the cycling life of rechargeable Zn‐air battery (RZAB). Herein, d‐band gap narrowing strategy is proposed to significantly boost the electrocatalytic activity and stability of spinel Co 3 O 4 for both oxygen reduction and evolution reactions. In situ Raman spectroscopy finds that the Ce atom substitution can significantly improve the durability and corrosion resistance of electrocatalysts in harsh alkaline electrolytes. Synchrotron X‐ray absorption fine structure reveals that the Co 3+ /Co 2+ ratio of Co 3 O 4 can be tuned with Ce introduction, which is beneficial to optimize the adsorption/desorption of the intermediates over Co oh 3+ active sites. Density functional theory calculations further confirm the reduced gap between Co d‐band and O p‐band centers, increased electrical conductivity, together with the deepened valence band maximum of Co sites in Ce‐doped Co 3 O 4 . Thereby, the optimized RZAB with Ce‐Co 3 O 4 delivers excellent long‐term durability (290 h) and large specific capacity (876.3 ), which possesses great prospects in all‐solid‐state flexible RZAB devices.