Entropy‐Stabilized Cation–Anion Vacancies Coupling in High‐Entropy Two‐Dimensional Crystals for Efficient Oxygen Evolution

ABSTRACT Despite their versatility, high‐entropy materials (HEMs) still lack precise control over coupled multisite defects in electrocatalysis, and their dynamic reaction mechanisms remain elusive. Here, we report an entropy‐stabilized cation–anion vacancies coupling strategy in high‐entropy metal phosphorus trisulfides (MPS 3 ), enabling semi‐quantitative control of coupled metal and sulfur vacancies within a single‐phase lattice. Such vacancies coupling induces asymmetric coordination environments and lattice distortion, facilitating optimization of oxygen evolution reaction (OER) intermediate adsorption. Operando Raman spectrum reveal that coupled vacancies promote earlier surface reconstruction with enhanced OH * adsorption, while suppressing excessive oxidation and metal dissolution, through electronegativity‐driven ionic migration. Density functional theory calculations uncover a spatially synergistic OER mechanism, in which vacancies‐activated Co‐centered edge motifs dominate OER kinetics with basal‐plane P sites providing a complementary pathway. As a result, (MnFeCoNiZn) 0.7 PS 3−δ (HE 0.7 PS 3−δ ) delivers an overpotential of 212 mV at 10 mA cm −2 , a Tafel slope of 28.6 mV dec −1 , and stable operation for 800 h at 200 mA cm −2 . In an alkaline electrolyzer, HE 0.7 PS 3−δ || Pt/C operates at 1.8 V at 1 A cm −2 at ≈80°C and maintains stable operation for 300 h at 0.5 A cm −2 . This work establishes entropy‐enabled cation–anion vacancies coupling as a general design principle for high‐performance electrocatalysis.