Preparation of CdS_ySe_1−y-MoS₂ Heterostructures via Cation Exchange of Pre-Epitaxially Synthesized Cu_2−χS_ySe_1−y-MoS₂ for Photocatalytic Hydrogen Evolution

Construction of 2D transition metal dichalcogenide (TMD)-based epitaxial heterostructures with different compositions is important for various promising applications, including electronics, photonics, and catalysis. However, the rational design and controlled synthesis of such kind of heterostructures still remain challenge, especially for those consisting of layered TMDs and other non-layered materials. Here, a facile one-pot, wet-chemical method is reported to synthesize Cu_2−χS_ySe_1−y-MoS₂ heterostructures in which two types of different epitaxial configurations, i.e., vertical and lateral epitaxies, coexist. The chalcogen ratio (S/Se) in Cu_2−χS_ySe_1−y and the loading amount of MoS₂ in the heterostructures can be tuned. Impressively, the obtained Cu_2−χS_ySe_1−y-MoS₂ heterostructures can be transformed to CdS_ySe_1−y-MoS₂ without morphological change via cation exchange. As a proof-of-concept application, the obtained CdS_ySe_1−y-MoS₂ heterostructures with controllable compositions are used as photocatalysts, exhibiting distinctive catalytic activities toward the photocatalytic hydrogen evolution under visible light irradiation. The method paves the way for the synthesis of different TMD-based lateral epitaxial heterostructures with unique properties for various applications.