Tailoring high-entropy alloys for cutting-edge hydrogen evolution electrocatalysis

This paper provides a general overview of high-entropy alloys (HEAs) as future electrocatalysts for the hydrogen evolution reaction (HER). Growing energy demands worldwide and the need to mitigate climate change have placed attention on the efficient, sustainable production of hydrogen through electrochemical water splitting.

Traditional noble-metal electrocatalysts such as platinum (Pt) possess excellent HER activity but are burdened by exorbitantly inhibitive cost, scarcity, and poisoning sensitivity. High-entropy alloys that consist of five or more major components in nearly equimolar proportions offer a paradigmatic solution due to their unique structural and electronic properties.

High configurational entropy, lattice distortion, sluggish diffusion, and synergistic "cocktail" effects, in combination, enhance the catalytic activity of these alloys. Improved synthesis techniques of HEAs in nanoparticle, nanowire, and porous network forms have been discovered to exhibit high HER activity with low overpotentials and long-term durability.

This review critically explores the fundamental principles of HER, the design principles of HEA electrocatalysts, and their applications in catalysis, with special focus on directions for future research to realize their full potential.