Interfacial Engineering Induced Charge Accumulation for Enhanced Solar Water Splitting

Efficient separation and extraction of charge carriers at the surface of semiconductor photoanodes play a pivotal role in enhancing the performance of solar‐driven photoelectrochemical (PEC) devices. Herein, a general strategy is presented to promote charge carrier migration by introducing a hole extraction layer, which enables dual‐interface engineering between the photoanode and the catalytic sites. This design enhances the transfer and accumulation of photogenerated holes from the semiconductor to the oxygen evolution cocatalyst (OEC). Specifically, FeNi‐LDH is inserted between α‐Fe 2 O 3 and a Ru‐based OEC, forming a cascaded α‐Fe 2 O 3 /FeNi‐LDH/Ru structure. This dual‐interface configuration facilitates directional charge transport, accelerates hole accumulation at Ru active sites, and suppresses carrier recombination. The optimized photoanode achieves a photocurrent density of 2.51 mA cm −2 at 1.23 V versus RHE, which is 3.8 times higher than that of pristine α‐Fe 2 O 3 . This work highlights the crucial role of rational interface engineering in regulating carrier dynamics and provides a broadly applicable strategy for constructing high‐efficiency PEC water‐splitting systems.