Crystal‐Interface‐Mediated Self‐Assembly of ZnIn₂S₄/CdS S‐scheme Heterojunctions Toward Efficient Photocatalytic Hydrogen Production

ABSTRACT Efficient photocatalytic water splitting can be significantly enhanced through the careful design of S‐scheme heterostructures, which play a pivotal role in optimizing performance. Herein, we report the construction of ZnIn₂S₄/CdS S‐scheme heterojunctions under ambient conditions, based on a sonochemical strategy. This structure is facilitated by the well‐matched interface between the (007) plane of layered ZnIn₂S₄ and the (101) plane of CdS, leading to a threshold optical response of 2.12 eV, which optimally aligns with visible light absorption. As a proof of concept, the resulting ZnIn₂S₄/CdS catalysts demonstrate a remarkable improvement in photocatalytic H₂ evolution, achieving a rate of 5678.2 μmol h⁻¹g⁻¹ under visible light irradiation (λ > 400 nm). This rate is approximately 10 times higher than that of pristine ZnIn₂S₄ nanosheets (NSs) and about 4.6 times higher than that of CdS nanoparticles (NPs), surpassing the performance of most ZnIn₂S₄‐based photocatalysts reported to date. Moreover, they deliver a robust photocatalytic performance during long‐term operation of up to 60 h, showing their potential for use in practical applications. Based on the theoretical calculation and experimental results, it is verified that the movements of electrons and holes in the opposite direction could be induced by the disparity in the work function and the internal electric field within the interfaces, thus facilitating the construction of S‐scheme heterojunctions, which fundamentally suppresses carrier recombination while minimizing photocorrosion of ZnIn₂S₄ toward enhanced photocatalytic behaviors.