Review on chemisorbed oxyanions on electrocatalysts for efficient oxygen evolution reaction

Oxygen evolution reaction (OER) seriously hinder the development of water electrolysis for the sluggish four proton-coupled electron transfer. Chemisorbed oxyanion engineering is a burgeoning hot topic for the promoted OER electrochemical performances by the electron structure modulation, optimal intermediate adsorption, fast proton transfer, strong pH buffer, high coordination energy and electrostatic repulsion to harmful anions. The formation and characterization of chemisorbed oxyanions are generalized to observe and confirm the chemisorption of oxyanions. The advantageous chemisorbed oxyanions are elaborated in forms of borate and its derivatives, nitrate, phosphate, sulfate, molybdate and other types of oxyanions. The electrocatalytic activities and stabilities of OER electrocatalysts with chemisorbed oxyanions have been significantly improved. However, some existing issues impede the advances of chemisorbed oxyanions, i.e., difficult identification of adsorption sites, lack of adsorption strength control, difficult control of adsorption amounts, unclear selective principle for multiple chemisorbed oxyanions. Therefore, the prospects are summarized in four points, i.e., (1) accurate prediction of adsorption sites based on oxygen vacancy formation, (2) precise control of adsorption strengths of oxyanions based on the physicochemical properties of metals, (3) precise control of adsorption amounts by suitable oxygen vacancies, (4) clarifying the selective principle for multiple chemisorbed oxyanions by the Lewis acidic-basic interaction. With the specific research directions and persevering endeavors, the mystery of chemisorbed oxyanions would be directly deciphered. Meanwhile, the development of OER electrocatalysts would be significantly promoted to meet the industrial water electrolysis requirement.