Directing Hole Utilization Through Self‐Reconstructed Crystallinity Differentiation for Photoelectrochemical Water Oxidation

Photoelectrochemical water oxidation is limited not simply by light absorption, but by inefficient hole routing and utilization at the semiconductor‐electrolyte interface, together with severe defect‐mediated recombination. Here, a self‐reconstructed crystallinity‐differentiated interface is developed to program hole utilization in photoanodes. A one‐step hydrothermal synthesis creates an interlocked architecture in which highly crystalline In 2 S 3 pyramids are coupled with a disordered mixed‐anion nanosheet domain, generating a spatially polarized reaction field for directed hole accumulation and transfer. This reconstructed interface lowers the work function, redistributes the local coordination environment around In sites, and induces a spatially heterogeneous photovoltage landscape that promotes interfacial charge separation. Mild Ar annealing further serves as a defect‐selective activation step, suppressing recombination‐active defects while preserving the beneficial interfacial polarization, thereby accelerating charge injection and oxygen evolution kinetics. The optimized photoanode reaches 8.74 mA cm −2 at 1.23 V RHE , establishing interlocked crystallinity‐differentiated architecture engineering combined with defect‐selective activation as an effective strategy for sulfide photoanodes.