Tuning and Shielding Iridium Active Sites Through Tungsten Electron Buffer for Oxygen Evolution Catalysis

ABSTRACT Efficient and durable oxygen evolution reaction (OER) electrocatalysts under acidic conditions are pivotal for proton‐exchange‐membrane water electrolysis (PEMWE), yet Ir‐based catalysts suffer from activity‐stability trade‐offs caused by facile over‐oxidation and corrosion. Herein, IrO x nanoclusters decorated with W single atoms (W SAs) and supported on N‐doped graphene (defined as W‐IrO x /NG) are synthesized via solvothermal reaction and NH 3 ‐assisted pyrolysis process. In W‐IrO x /NG, W SAs with W–N 3 O 1 configuration are attached onto IrO x nanoclusters through W─O─Ir linkers, forming interfacial covalent connections for efficient charge transfer. W‐IrO x /NG delivers an ultrahigh mass activity of 2998.91 A g Ir −1 at 300 mV overpotential and maintains stable operation for over 250 h at 1 A cm −2 in a PEM electrolyzer with an ultralow Ir loading (0.25 mg Ir cm −2 ). Mechanistic insight analysis uncovers that W atoms serve as electron buffer, donating and storing electrons to regulate the oxidation state of Ir during OER, thereby suppressing irreversible over‐oxidation. Theoretical calculation demonstrates that W SAs with W─N 3 O 1 sites modulate the d ‐band structure of Ir center, lowering the deprotonation barrier of *OH/*OOH intermediates and simultaneously weakening oxo‐species adsorption strength, thus accelerating OER kinetics.