Boosting Reaction Kinetics and Mass Transfer of Bifunctional Co‐Based Oxygen Electrocatalyst Prepared from CoAl‐LDH

Abstract

AbstractThe simultaneous optimization of sluggish reaction kinetics and mass transfer in bifunctional oxygen electrocatalysts for air cathodes remains a great challenge. This study utilizes CoAl‐layered double hydroxide as a metal precursor to fabricate a bifunctional oxygen electrocatalyst, denoted as CoAlOXD‐Thin. This electrocatalyst features a specific core–shell structure of Co species, which grows on an aerophilic and conductive substrate composed of Al2O3 and carbon. It is successfully demonstrated that the thickness of Co@Co3O4 core–shell structure can be easily controlled by selecting different precursors and the combination of Co core and Co3O4 shell optimizes the adsorption strength of intermediates, leading to enhanced catalytic performance. Additionally, the Al species plays a dual role. It not only facilitates the mass transfer of oxygen species but also hinders the 2e− pathway of oxygen reduction reaction, leading to improved selectivity. Notably, the Zn–air batteries utilizing CoAlOXD‐Thin demonstrate an impressive peak power density of 216.2 mW cm−2, a high specific capacity of 800.8 mAh gZn−1, and excellent cycling stability and reversibility, surpassing those of the Pt/C + RuO2 catalyst. This study presents a novel approach to enhance air cathode performance by optimizing reaction kinetics and mass transfer through precursor design.