Efficient Mechanochemical Preparation of Graphene-Like Molybdenum Disulfide and Graphene-Based Composite Electrocatalysts for Hydrogen Evolution Reaction

Graphene-like MoS 2 and graphene-based (gMoS 2 /Gr, Gr@gMoS 2 , and gMoS 2 @Gr) nanocomposites, which are able to operate as electrocatalysts of water splitting with hydrogen evolution, were prepared by solventless mechanochemical delamination of bulk molybdenum disulfide and graphite. It was shown that the sequence of nanostructuring significantly affects both the morphology and the electrocatalytic properties of the prepared nanocomposites. The material prepared by sequential mechanochemical treatment of molybdenum disulfide and graphite—gMoS 2 @Gr—is characterized by significant delamination of both components with nearly complete disruption of the layer ordering, few-layer MoS 2 nanoparticles with higher degree of defectiveness, the graphene component with sufficiently large ordered regions, due to which it exhibited the best electrocatalytic performance with the Tafel slope of 60 mV/dec and the overvoltage of 195 mV at the current density of 10 mA/cm 2 (or specific current ~ 17 A/g). It was shown that gMoS 2 @Gr nanocomposite as HER electrocatalyst can be used as an effective counter electrode in photoelectrochemical cells, providing the photocurrent of 1 mA/cm 2 at the voltage of 365 mV. As a whole, the presented data show that gMoS 2 @Gr nanocomposite is an efficient HER electrocatalyst attractive due to the simplicity and cheapness of its preparation provided by the mechanochemical approach. Graphical Abstract