In Situ Photoelectrochemical Chelation Programs Defect‐Resilient Coordination Microenvironments for Enhanced Water Oxidation

ABSTRACT Deep‐level defects function as non‐radiative recombination centers that throttle oxygen evolution reaction (OER) kinetics. Conventionally, static and pre‐deposited passivation layers often fail during operation, disconnecting defect suppression from the creation and sustained maintenance of catalytically competent sites. Here, we address this limitation with a photoelectrochemically‐driven microenvironment strategy that selectively manipulates the first coordination shell of surface Zn on ZnIn 2 S 4 . Under the in situ photoelectrochemical chelation process, hydroxyethylidene diphosphonic acid writes robust Zn–O–P motifs that subtly distort the Zn–S framework and convert deep traps into shallow states, thereby accelerating charge transfer while suppressing recombination. Density functional theory suggests that Zn–O–P lowers the OER overpotential and switches the rate‐determining step from O * →OOH * to OOH * →O 2 via stabilized * OOH intermediates. The optimized photoanode delivers a photocurrent density of 5.38 mA cm −2 at 1.23 V RHE , surpassing previously reported ZnIn 2 S 4 ‐based photoanodes. By unifying in situ deep‐trap management and active site construction along a single chemical pathway, this work establishes a modular and general route for dynamic defect engineering and active site reconfiguration, advancing defect‐tolerant innovations in energy conversion and storage.