Internal electric field-driven interfacial charge transfer and enhanced photocatalytic hydrogen evolution in...

To address the prevalent problems of rapid photogenerated carrier recombination and insufficient redox capacity in photocatalytic hydrogen evolution, this work constructs a ZnWO₄/Mn_0.2Cd_0.8S (ZWO/MCS) heterojunction photocatalyst featuring an S-scheme band structure. The addition of ZnWO₄ (ZWO) significantly boosts the photocatalytic activity of Mn_0.2Cd_0.8S (MCS). Under irradiation with simulated visible light, the 20ZWO/MCS composite exhibited the highest hydrogen production rate (30.22 mmol·g^-1·h^-1), 44.44 times that of pure ZWO and 4.51 times that of pure MCS, respectively. It also demonstrates excellent catalytic stability during continuous cycling tests. Through a systematic investigation of its structure, optoelectronic properties, and photocatalytic hydrogen evolution performance, combined with density functional theory (DFT) theoretical calculations, it was confirmed that a tight heterointerface forms between ZWO and MCS, establishing an S-scheme interfacial charge transfer route driven by the internal electrical field (IEF). Through the pathway, the photogenerated charges are efficiently separated spatially, with electrons enriched in the conduction band of MCS for proton reduction for hydrogen production, while holes gather within the valence band of ZWO. The study deepens the understanding of the behavior of charge carriers in S-scheme heterojunctions regarding their separation and migration, providing theoretical foundations and material design strategies for developing high-performance photocatalytic systems.