Preparation of CdS y Se 1− y ‐MoS 2 Heterostructures via Cation Exchange of Pre‐Epitaxially Synthesized Cu 2− χ S y Se 1− y ‐MoS 2 for Photocatalytic Hydrogen Evolution

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.