Synthesis of Cu_2‐xSe‐MoSe₂ Edge‐Epitaxial Heterostructure for Efficient Electrocatalytic Hydrogen Evolution

Abstract The exposure of active edge sites of transition metal dichalcogenide (TMD) in TMD‐based heterostructures is essential to enhance the catalytic activity toward electrochemical catalytic hydrogen evolution (HER). The construction of TMD‐based edge‐epitaxial heterostructures can maximally expose the active edge sites. However, owing to the 2D crystal structures, it remains a great challenge to vertically align layered TMDs on non‐layered metal chalcogenides. Herein, the synthesis of Cu_2‐xSe‐MoSe₂ edge‐epitaxial heterostructure is reported by a facile one‐pot wet‐chemical method. A high density of MoSe₂ nanosheets grown vertically to the <111>_Cu2‐xSe on the surface of Cu_2‐xSe nanocrystals is observed. Such edge‐epitaxial configuration allows the exposure of abundant active edge sites of MoSe₂ and enhances the changer transfer between MoSe₂ and Cu_2‐xSe. As a result, the obtained Cu_2‐xSe‐MoSe₂ epitaxial heterostructures show excellent HER performance as compared to that of Cu_2‐xSe@1T/2H‐MoSe₂ core@shell heterostructure with similar size. This work not only offers a novel approach for designing efficient electrochemical catalysis but also enriches the diversity of TMD‐based heterostructures, holding promise for various applications in the future.