Preparation of CdSy Se1- y -MoS2 Heterostructures via Cation Exchange of Pre-Epitaxially Synthesized Cu2- χ Sy Se1- y -MoS2 for Photocatalytic Hydrogen Evolution

Synthesis of Cu2-xSe-MoSe2 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 Cu2-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 Cu2-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 Cu2-xSe. As a result, the obtained Cu2-xSe-MoSe2 epitaxial heterostructures show excellent HER performance as compared to that of Cu2-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.

2D Transition Metal Dichalcogenides for Photocatalysis

Two-dimensional (2D) transition metal dichalcogenides (TMDs), a rising star in the post-graphene era, are fundamentally and technologically intriguing for photocatalysis. Their extraordinary electronic, optical, and chemical properties endow them as promising materials for effectively harvesting light and catalyzing the redox reaction in photocatalysis. Here, we present a tutorial-style review of the field of 2D TMDs for photocatalysis to educate researchers (especially the new-comers), which begins with a brief introduction of the fundamentals of 2D TMDs and photocatalysis along with the synthesis of this type of material, then look deeply into the merits of 2D TMDs as co-catalysts and active photocatalysts, followed by an overview of the challenges and corresponding strategies of 2D TMDs for photocatalysis, and finally look ahead this topic.

Heterojunction Design between WSe2 Nanosheets and TiO2 for Efficient Photocatalytic Hydrogen Generation

Design and fabrication of efficient and stable photocatalysts are critically required for practical applications of solar water splitting. Herein, a series of WSe2/TiO2 nanocomposites were constructed through a facile mechanical grinding method, and all of the nanocomposites exhibited boosted photocatalytic hydrogen evolution. It was discovered that the enhanced photocatalytic performance was attributed to the efficient electron transfer from TiO2 to WSe2 and the abundant active sites provided by WSe2 nanosheets. Moreover, the intimate heterojunction between WSe2 nanosheets and TiO2 favors the interfacial charge separation. As a result, a highest hydrogen evolution rate of 2.28 mmol/g·h, 114 times higher than pristine TiO2, was obtained when the weight ratio of WSe2/(WSe2 + TiO2) was adjusted to be 20%. The designed WSe2/TiO2 heterojunctions can be regarded as a promising photocatalysts for high-throughput hydrogen production.