Dynamic Deprotonation Enhancement Triggered by Accelerated Electrochemical Delithiation Reconstruction during Acidic Water Oxidation.

Abstract

The structure-dependent transition in reaction pathways during acidic oxygen evolution (OER) is pivotal due to the active site oxidation accompanied by the coordination environment changes. In this work, charge-polarized Ir-O-Co units are constructed in alkali metal cobalt oxides (LiCoO₂, and Na_0.74CoO₂) to modify the lower Hubbard band. Benefiting from the accelerated delithiation reconstruction induced by the altered band structure, typical Ir-LiCoO₂ produces high-valent Ir sites with unsaturated coordination through the charge compensation during OER. Oxygen atoms shared by trimetallic sites exhibit strong Bro̷nsted acidity, promoting proton migration for unsaturated Ir sites and dynamically enhancing deprotonation. Furthermore, the stable coordination environment, along with electron donation from Co sites, significantly improves the stability of Ir sites. The unique electrochemical activation results in a low overpotential of 190 mV at 10 mA cm^-2 during acidic OER and delivers exceptional stability at 1 A cm^-2 for 150 h with a slight voltage degradation in a proton exchange membrane electrolyzer. This work provides in-depth insights into the relationship between catalyst reconstruction and reaction mechanisms.