Ultrafast electron transfer at the ZnIn₂S₄/MoS₂ S-scheme interface for photocatalytic hydrogen evolution

The performance of any photocatalyst relies on its solar harvesting and charge separation characteristics. Fabricating the S-scheme heterostructure is a proficient approach for designing next-generation photocatalysts with improved redox capabilities. Here, we integrated ZnIn₂S₄ (ZIS) and MoS₂ nanosheets to develop a unique S-scheme heterostructure through an in situ hydrothermal technique. The designed ZIS/MoS₂ heterostructure showcased a 2.8 times higher photocatalytic H₂ evolution rate than pristine ZIS nanosheets. The steady-state optical measurements revealed enhanced visible light absorption and reduced charge recombination in the heterostructure. Transient absorption (TA) spectroscopy revealed the interfacial electron transfer from ZIS to MoS₂. The X-ray photoelectron and electron/hole quenching TA spectroscopic measurements collectively confirmed the integration of both semiconductors in an S-scheme manner, facilitating enhanced H₂ production in the case of the heterostructure. This study highlights the importance of in-depth spectroscopic investigations in advancing the photocatalytic performance of S-scheme heterostructure-based photocatalysts.