High‐Entropy Alloys for Photocatalysis: From Cocatalyst Engineering to Multifunctional Active Platforms

Abstract

Photocatalysis has emerged as a promising approach for solar energy conversion and environmental remediation. However, its practical implementation is still hindered by limited charge‐separation efficiency, slow surface reaction kinetics, and insufficient catalyst stability. High‐entropy alloys (HEAs), with their complex multicomponent structures, lattice distortion, diverse atomic environments, and tunable electronic properties, have gained significant attention as a new class of photocatalytic materials. This review summarizes recent advancements in HEAs‐based photocatalysis, focusing on key characteristics that enhance photocatalytic performance, including entropy stabilization, electronic structure modulation, surface‐site heterogeneity, and interfacial charge‐transfer behavior. HEAs function both as cocatalysts with semiconductor photocatalysts and as direct catalytic phases in photocatalytic and photo‐Fenton processes. Applications include hydrogen evolution, CO 2 conversion, pollutant degradation, and advanced oxidation reactions. The review also critically addresses current challenges such as precise composition control, active‐site identification, mechanistic understanding under operating conditions, standardized performance evaluation, and long‐term stability. Finally, it discusses future research directions, including theory‐guided compositional design, operando characterization, scalable synthesis, and integration into practical solar‐energy systems.