Multi‐Site Contact Schottky Junctions with Improved Light Adsorption Enable Efficient Carrier Transport for Photoelectrocatalytic Water Oxidation

ABSTRACT Photoelectrocatalytic (PEC) water splitting enables sustainable solar‐to‐hydrogen conversion, yet bismuth tungstate (Bi 2 WO 6 ) photoanodes suffer from severe charge recombination. Herein, we rationally design a novel multi‐site contact Schottky junction with modulated interfacial electronic structure and multi‐site charge transport channels by integrating 2D Fe‐doped Bi 2 WO 6 (Fe‐BWO) nanosheets with 3D RuCu co‐doped WC (RuCu‐WC) dodecahedra. The polyhedral scaffold forms multiple discrete yet intimate contact points at its vertices and edges, constructing abundant parallel electron extraction channels. The introduction of Fe broaden the light harvesting efficiency endowing with an improved interfacial carrier density. Driven by the large work function difference, a strong interfacial built‐in electric field is established, which unidirectionally drives photogenerated electrons from band‐narrowed Fe‐BWO into the interconnected 3D RuCu‐WC conductive network while spatially confining photogenerated holes on the Fe‐BWO basal plane to drive the water oxidation reaction. The optimized photoanode delivers an exceptional photocurrent density of 7.40 mA cm −2 at 1.23 V vs. reversible hydrogen electrode (RHE) with 66.1% charge transfer efficiency. The assembled PEC water splitting cell achieves a remarkable photocurrent density of 6.39 mA cm −2 at 1.23 V and a solar‐to‐hydrogen (STH) conversion efficiency of 5.59%. This work provides a generalizable strategy for enhancing charge separation in semiconductor‐based energy conversion systems.