Electrocatalytic Mechanism of Defect in Spinels for Water and Organics Oxidation

Abstract

Spinels display promising electrocatalytic ability for oxygen evolution reaction (OER) and organics oxidation reaction because of flexible structure, tunable component, and multifold valence. Unfortunately, limited exposure of active sites, poor electronic conductivity, and low intrinsic ability make the electrocatalytic performance of spinels unsatisfactory. Defect engineering is an effective method to enhance the intrinsic ability of electrocatalysts. Herein, the recent advances in defect spinels for OER and organics electrooxidation are reviewed. The defect types that exist in spinels are first introduced. Then the catalytic mechanism and dynamic evolution of defect spinels during the electrochemical process are summarized in detail. Finally, the challenges of defect spinel electrocatalysts are brought up. This review aims to deepen the understanding about the role and evolution of defects in spinel for electrochemical water/organics oxidation and provide a significant reference for the design of efficient defect spinel electrocatalysts.

Modulation Strategies and Activity Descriptors of Spinel Electrocatalysts for Lithium−Oxygen Batteries

“…The vacancy defects in AB 2 O 4 spinel can effectively regulate the coordination environment and electronic structure of the active site, which has a significant contribution towards the enhancement of the catalytic activity of the material. [99][100][101] Specifically, vacancy defect engineering involves the removal of small amounts of metal cations (cationic defects) or oxygen anions (anionic defects) in AB 2 O 4 to achieve a change in physicochemical properties of original spinel, which accelerates the rate of electron transfer and modulates the adsorption capacity of the intermediates in the reaction, providing a viable direction to obtain high-efficiency electrocatalysts. Typically, inducing cation vacancy defects in spinel significantly modulates its electronic structure, optimizes the density of states (DOS) near the Fermi energy level, and accelerates the charge transfer rate, eventually enhancing the OER reaction kinetics to large extent.…”

Accelerating materials discovery for electrocatalytic water oxidation via center-environment deep learning in spinel oxides

“…6,[8][9][10] Alkaline water electrolysis, in particular, has been extensively researched due to its simple structure and low-cost electrode materials. [11][12][13] This reaction typically comprises two halfreactions: the OER at the anode [14][15][16][17][18][19] and the hydrogen evolution reaction (HER) at the cathode. 20 The OER half-reaction at the anode has a lower reaction rate due to the slow kinetics of its four-electron transfer process, [21][22][23] overall limiting the efficiency of the OER; [24][25][26][27] hence developing efficient OER catalysts is of signicant importance.…”