Oxygen-incorporated MoS2 ultrathin nanosheets grown on graphene for efficient electrochemical hydrogen evolution

Abstract

MoS2 has emerged as an efficient hydrogen evolution catalyst and its activity is believed to be mainly determined by two factors: the amount of edge sites and electrical conductivity. To achieve improved catalytic activity, the few-layered oxygen-incorporated MoS2 ultrathin nanosheets are prepared for the construction of hybrid nanosheets with graphene substrates using one-pot hydrothermal method for the first time. XRD, Raman, SEM, TEM, EDS and TGA techniques are used to characterize the hybrids. The moderate oxygen-incorporation into MoS2 creates abundant edge sites and improves the conductivity. The tight coupling between the hybrid nanosheets expedites the electrical transfer. Endowed with the above advantages, the hybrid nanosheets are ideal electrocatalysts for hydrogen evolution reaction (HER) and exhibit high activity, which is demonstrated by the ultralow onset overpotential (120 mV), large cathodic current density (65.5 mA cm−2 at η = 300 mV), and small Tafel slope (51 mV decade−1), as well as superior cycling stability. Our enhanced understanding of this highly active MoS2 hybrid catalyst for HER may facilitate the development of economical electrochemical hydrogen production systems.