Synergistic Effect of Atomic‐Scale Interface Engineering and Built‐In Electric Field at S‐Scheme Bi 2 WO 6 /ZnIn 2 S 4 Heterojunctions for Photocatalytic Hydrogen Evolution

A novel S‐scheme heterojunctions are fabricated via in situ growth of ZnIn 2 S 4 (ZIS) nanoflakes on Bi 2 WO 6 (BWO) assembled nanorods, forming Bi 2 WO 6 /ZnIn 2 S 4 (BWIS) heterostructure with a nanoflake‐assembled morphology. The resulting BWIS architecture demonstrated significantly enhanced light‐harvesting capacity, enhanced photocurrent response, and photocatalytic hydrogen evolution activity. The optimized BWIS system exhibited a remarkable photocatalytic hydrogen generation rate of 392 µmol. g −1 . h −1 , representing an enhancement of 24.5‐fold compared to pristine BWO, with an Apparent Quantum Yield of ≈53% at 420 nm. A well‐aligned band structure and work function difference between BWO and ZIS generate a built‐in electric field, facilitating directional S‐scheme charge transfer from BWO to ZIS. The internal field significantly improves charge separation and transport kinetics, as evidenced by femtosecond transient absorption spectra and time‐resolved photoluminescence spectra. Furthermore, density functional theory (DFT) calculations reveal that the reduced band gap in the BWIS heterostructure facilitates efficient photocatalytic water splitting. This work underscores the pivotal role of atomic‐scale interface engineering and internal electric field optimization in designing S‐scheme heterostructures for superior photocatalytic hydrogen production.