Solution-Processed Hybrid Graphene Flake/2H-MoS₂ Quantum Dot Heterostructures for Efficient Electrochemical Hydrogen Evolution

Abstract

We designed solution-processed, flexible hybrid graphene flake/2H-MoS2\nquantum dot (QD) heterostructures, showing enhanced electrocatalytic activity\nfor the hydrogen evolution reaction (HER) with respect to their native\nindividual components. The 2H-MoS2 QDs are produced through a scalable,\nenvironmentally friendly, one-step solvothermal approach from two-dimensional\n(2D) 2H-MoS2 flakes obtained by liquid phase exfoliation (LPE) of their bulk\ncounterpart in 2-Propanol. This QDs synthesis avoids the use of high boiling\npoint and/or toxic solvents. Graphene flakes are produced by LPE of graphite in\nN-Methyl-2-pyrrolidone. The electrochemical properties of 2H-MoS2 QDs and their\nHER-favorable chemical and electronic coupling with graphene enable to reach a\ncurrent density of 10 mA/cm^2 at an overpotential of 136 mV, surpassing the\nperformances of graphene flake/2H-MoS2 (1T-MoS2) flake heterostructures. Our\napproach provides a shortcut, viable and cost-effective method for enhancing\nthe 2D materials electrocatalytic properties.\n