High-entropy oxides for energy-related electrocatalysis

Electrocatalysis plays a crucial role in the conversion and storage of renewable energy, offering significant potential for addressing the energy crisis and environmental concerns. High-entropy oxides (HEOs), a class of emerging functional materials, have gained increasing attention in electrocatalysis due to their stable crystal structure, exceptional geometric compatibility, unique electronic balance factors, and abundant active sites. In this comprehensive review, we present recent advancements in utilizing HEOs as catalysts for various energy-based electrocatalytic reactions. We begin with an overview of HEOs that includes definitions, fundamental properties, and theoretical investigations. Subsequently, we describe different synthetic methods for HEOs while highlighting two newly-developed techniques. Furthermore, we extensively discuss recent developments in HEO-based electrocatalysts with diverse crystal structures such as rock-salt-type, rutile-type, spinel-type, perovskite-type, and other specially-structured HEOs. Special emphasis is placed on designed strategies aimed at enhancing performance and exploring correlations between structure/ composition and electrocatalytic performance. Finally, we provide concluding remarks along with perspectives on future opportunities in this exciting field.