Inactive Ag Modification and Defect Engineering Optimization on Three-Dimensional Coral-Like High-Entropy Oxides to Trigger Effective Oxygen Evolution Reaction

Abstract

AbstractsHigh-entropy materials (HEMs) have emerged as promising candidates in electrocatalysis, owing to their synergistic multielement composition, structural versatility, and excellent electron transport properties. High-entropy oxide (HEO), as one of the most prevalent HEMs, have received great attention due to their excellent physical and chemical properties, but challenges remain in achieving optimal high-entropy configurations and ensuring sufficient active site availability. In this report, we proposed a high-entropy conformation strategy incorporating inactive Ag modification coupled with high-temperature annealing treatment to obtained a unique high-entropy oxide NiFeCrCoAgO (HEO-400) with coral -like hierarchical structure. Thanks to the unique coral-like hierarchical structure and abundant oxygen vacancies (OV) of the high-entropy HEO-400, the obtained catalysts show high activity for the oxygen evolution reaction (OER) in 1.0 M KOH solution with low overpotential of 308 mV at a current density of 100 mA cm-2, small Tafel slope of 57 mV dec-1, together with robust electrocatalytic stability, outperforming most of the reported electrocatalysts and the commercial catalyst RuO2. The excellent structural and catalytic properties were further demonstrated by density functional theory (DFT) calculations. This work not only creates an excellent HEO electrocatalyst for oxygen evolution reaction in alkaline media, but also contributes novel insights into the design of conformational strategies for high-entropy catalysts.

Keywords: High-entropy electrocatalysis, High-entropy oxides, Ag modification, Oxygen vacancies, Oxygen evolution reaction