High‐Entropy‐Induced Lattice Distortion Activates Dual‐Cobalt Site Synergy for Boosted Photo(Electro)Catalytic Hydrogen Evolution

Abstract

ABSTRACT High‐entropy engineering breaks the activity–stability trade‐off in solar water splitting. We design a spinel oxide (CuCoNi)(GaCoCrMnFe) 2 O 4 with lattice distortion ( δ avg = 3.35%) and stabilized Co tet 2+ /Co oct 3+ dual sites. The cocktail effect goes beyond elemental averaging: Cu/Ga harvest light; Co enables dual‐site surface catalysis; Ni/Cr induce distortion and local built‐in fields; Cu/Mn trigger Jahn–Teller upshifting the d‐band center; Fe/Mn balance distortion; multivalent species provide a broad redox window. The material achieves a photocatalytic HER rate of 16.62 µmol∙h −1 ∙g −1 —16.3× that of Co 3 O 4 and 10.8× that of CuGa 2 O 4 , alongside <5% decay over 30 h. In photoelectrochemical tests, it delivers 2.03 mA∙cm −2 at 0 V RHE in neutral electrolyte (21.6× and 67.7× the benchmarks) and 7.08 mA∙cm −2 under alkaline conditions with 48% IPCE and 0.56% HC‐STH. Distortion‐induced dipoles (0.87 D) extend carrier lifetime to 6.95 ns; Co tet 2+ dissociates water ( E a = 0.187 eV) while Co oct 3+ reduces protons ( ΔG *H = 0.288 eV); configurational entropy (2.71 R ) stabilizes the structure. This “entropy–structure–function” strategy offers a generalizable route to durable, high‐performance solar fuel catalysts.