Synthesis of Cu 2-x Se-MoSe 2 Edge-Epitaxial Heterostructure for Efficient Electrocatalytic Hydrogen Evolution.

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-x Se-MoSe 2 edge-epitaxial heterostructure is reported by a facile one-pot wet-chemical method. A high density of MoSe 2 nanosheets grown vertically to the <111> Cu2-xSe on the surface of Cu 2-x Se nanocrystals is observed. Such edge-epitaxial configuration allows the exposure of abundant active edge sites of MoSe 2 and enhances the changer transfer between MoSe 2 and Cu 2-x Se. As a result, the obtained Cu 2-x Se-MoSe 2 epitaxial heterostructures show excellent HER performance as compared to that of Cu 2-x Se@1T/2H-MoSe 2 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.