Remarkable photochemical HER activity of semiconducting 2H MoSe2 and MoS2 covalently linked to layers of 2D structures and of the stable metallic 1T phases prepared solvo- or hydro-thermally
MoS2 and MoSe2 in the stable semiconducting 2H form show negligible photocatalytic activity for the hydrogen evolution reaction (HER). By linking the layers of the dichalcogenide with layers of other 2D materials such as carbon-rich borocarbonitride (BC7N), one can enhance the photochemical HER activitysignificantly. Interestingly, such nanocomposites, MoSe2–MoSe2 and MoSe2–BCN show high photocatalytic activity even though the dichalcogenide itself is in the 2H form. This study shows the important role played by covalent cross-linking of layered compounds. Photocatalytic activity of covalently cross-linked layer of 2H-MoSe2 is higher than that of 2H-MoS2. Unlike the 2H forms, the metallic 1T forms of MoS2 and MoSe2 prepared by lithium intercalation followed by exfoliation, exhibit high photocatalytic HER activity. Unfortunately, materials prepared by lithium intercalation are unstable. The 1T forms of MoSe2 and MoS2 prepared by solvothermal or hydrothermal methods are, however, quite stable and exhibit good photochemical activity for HER. The 1T forms are generally superior to the covalently linked 2H forms. The present study shows how MoSe2 and MoS2 in both 2H and 1T forms can be exploited for photochemical HER activity by appropriate chemical manipulation.
Volume 134, 2022
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