High‐Density Cationic Defects Coupling with Local Alkaline‐Enriched Environment for Efficient and Stable Water Oxidation

Abstract The inferior activity and stability of non‐noble metal‐based electrocatalysts for oxygen evolution reaction (OER) seriously limit their practical applications in various electrochemical energy conversion systems. Here we report, a drastic nonequilibrium precipitation approach to construct a highly disordered crystal structure of layered double hydroxides as a model OER catalyst. The unconventional crystal structure contains high‐density cationic defects coupled with a local alkaline‐enriched environment, enabling ultrafast diffusion of OH − ions and thus avoiding the formation of a local acidic environment and dissolution of active sites during OER. An integrated experimental and theoretical study reveals that high‐density cationic defects, especially di‐cationic and multi‐cationic defects, serve as highly active and durable catalytic sites. This work showcases a promising strategy of crystal structure engineering to construct robust active sites for high‐performance oxygen evolution in an alkaline solution.