Design\nof MoS₂/Graphene van der Waals Heterostructure\nas Highly Efficient and Stable Electrocatalyst for Hydrogen Evolution\nin Acidic and Alkaline Media

Abstract

The\nthermodynamically stable phase of molybdenum disulfide (MoS₂) is evaluated as a promising and durable nonprecious-metal\nelectrocatalyst toward the hydrogen evolution reaction (HER); however,\nits actual catalytic activity is restricted by an inert basal plane,\nlow electronic conductivity, low density, and using efficiency of\nedged atoms. Moreover, 2D/2D van der Waals (vdws) heterostructures\n(HSs) with face-to-face contact can construct a highly coupled interface\nand are demonstrated to have immense potential for catalytic applications.\nIn the present work, a 2D/2D hetero-layered architecture of an electrocatalyst,\nbased on the alternate arrangement of ultrasmall monolayer MoS₂ nanosheets (approximately 5–10 nm) and ultrathin graphene\n(G) sheets, is prepared by a facilely chemical process, which is named\nas MoS₂/G HS. The unique structural characteristic of MoS₂/G HS is in favor of accommodating more active sites as the\ncenters of ad/desorption hydrogen and transferring and separating\nthe charges at a coupled interface to improve the electronic conductivity\nand durability. The density functional theory calculation results\nfurther confirm that the alternately arranged G layers and MoS₂ monolayers, as well as the expanded interplanar distance\nof 1.104 nm for MoS₂/G HS, can exhibit a superior HER performance\nin both 0.5 M H₂SO₄ and 1.0 M KOH.