Strain Engineering in High‐Entropy Electrocatalysts: Mechanisms, Strategies and Water Splitting Applications

Strain engineering has emerged as an effective strategy for tailoring the electronic structure and catalytic behavior of materials at the atomic scale. For electrochemical water splitting, the sluggish kinetics of the hydrogen evolution reaction and oxygen evolution reaction are largely limited by scaling relationships and nonoptimized adsorption energetics of key intermediates. High‐entropy materials, featuring multiprincipal‐element compositions and pronounced lattice distortion, offer a unique platform for strain‐mediated catalytic regulation. Their intrinsic microstrain fields, derived from atomic size mismatch together with sluggish diffusion and cocktail effects, enable tunable electronic structures and abundant metastable active sites. This review summarizes recent advances in strain engineering of high‐entropy materials for water splitting. Fundamental concepts of strain and its influence on d‐band centers, adsorption energetics, and reaction kinetics are first introduced. This is followed by a discussion of strain modulation strategies, including doping, solid solution alloying, and defect engineering. Special emphasis is placed on the distinct behavior of high‐entropy materials compared with conventional alloys, particularly their nonlinear electronic hybridization and multisite synergy. Finally, key challenges involving strain quantification, operando evolution, and strain‐entropy coupling are highlighted, providing guidance for the rational design of next‐generation water‐splitting catalysts.