The roles of oxygen vacancies in electrocatalytic oxygen evolution reaction

The efficiency of many rechargeable energy storage technologies and hydrogen production from water splitting is limited by the oxygen evolution reaction (OER) due to its sluggish kinetics. Understanding the characteristics of the material that affect OER activity is of paramount importance for the development of high-efficiency electrocatalysts for OER. Oxygen vacancy engineering is an effective approach to tune the electronic structure of electrocatalysts and the surface absorption/desorption of reactants, and the important roles of oxygen vacancies play in electrocatalytic OER have been demonstrated by many groups. To make the oxygen vacancy effect clear, the recent development of manipulating the oxygen vacancies in electrocatalysts for enhancing OER performance is reviewed here and the proposed mechanisms for the enhanced performance are discussed in detail. Various approaches for generating oxygen vacancies in electrocatalysts and characterization methods for oxygen vacancies are also summarized. Furthermore, the challenges in designing high-efficient OER electrocatalysts and outlooks in understanding the oxygen vacancy-activity relationship are discussed.