▎ 摘　　要

The successful designing of low-cost and highly active electrocatalytic materials from earth-abundant elements are favorable for the large scale production of hydrogen from water splitting. Herein, the controllable sandwiching of reduced graphene oxide (RGO) in hierarchical defect-rich MoS2 ultrathin nanosheets (MoSGMoS) with vertical alignment and expanded interlayer spacing is synthesized by hydrothermal method. The MoSGMoS product exhibits outstanding electrocatalytic activity for hydrogen evolution reaction (HER) with an onset overpotential of 24.3 mV, low overpotentials of 72 mV at 10 mA cm(-2) and 384 mV at 1300 mA cm(-2), a small Tafel slope of 44.7 mV decade(-1), large exchange current density of 0.67 mA cm(-2), and high durability in H2SO4 solution. The HER performance of the MoSGMoS catalyst is much better than most of the reported MoS2-based catalysts, especially in terms of onset overpotential and cathodic current density. The synergistic effect between defect-rich MoS2 ultrathin nanosheets with hierarchical structure, vertical alignment and expanded interlayer spacing, and conductive RGO is responsible for the outstanding HER activity. This method may open a new way to grow hierarchical MoS2 nanosheets on carbonaceous materials for enhanced hydrogen production from water splitting.