1T/2H MoS ₂ Functional Layer Boosts HER Kinetics of LaFeO ₃ Photocathode in Neutral Media through Hydrogen Spillover and Surface State Regulation

Abstract LaFeO ₃ (LFO), a typical p‐type semiconductor, is an attractive cathode material for PEC water splitting due to its suitable energy band structure and compositional flexibility. However, serious carrier recombination and sluggish charge/proton transfer kinetics have severely limited its application, especially under neutral conditions. To address these issues, Co‐doped LFO (Co‐LFO) is first employed to modulate the electronic structure and enhance charge transport properties. Subsequently, an innovative 2H‐1T MoS ₂ homojunction functional layer (1T‐2H MoS ₂ ) is innovatively introduced on the basis of Co‐doped LFO (Co‐LFO/1T‐2H MoS ₂ ). Optical and electrochemical characterization shows that the 2H‐phase MoS ₂ forms a type‐II heterojunction with Co‐LFO to enhance the photogenerated carrier separation efficiency while broaden the light absorption range of the catalyst. Furthermore, experiments and DFT calculations indicated that 2H‐1T MoS ₂ accelerated the charge separation/transfer dynamics of the Co‐LFO photocathode through hydrogen spillover and surface state modulation. Benefitting from the combined effects of Co‐doping and the 1T‐2H MoS ₂ functional layer, the prepared Co‐LFO/1T‐2H MoS ₂ photocathode exhibits a superior photocurrent density of −3.35 mA cm ⁻² at 0 V (vs RHE) in PBS with pH 7.0. This study provides guidance for modulating the interfacial electronic and geometrical structure of heterostructured photocathodes.