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

Abstract

Abstract The 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 CoAl OXD ‐Thin. This electrocatalyst features a specific core–shell structure of Co species, which grows on an aerophilic and conductive substrate composed of Al 2 O 3 and carbon. It is successfully demonstrated that the thickness of Co@Co 3 O 4 core–shell structure can be easily controlled by selecting different precursors and the combination of Co core and Co 3 O 4 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 CoAl OXD ‐Thin demonstrate an impressive peak power density of 216.2 mW cm −2 , a high specific capacity of 800.8 mAh g Zn −1 , and excellent cycling stability and reversibility, surpassing those of the Pt/C + RuO 2 catalyst. This study presents a novel approach to enhance air cathode performance by optimizing reaction kinetics and mass transfer through precursor design.