▎ 摘　　要

It is universally acknowledged that the development of high-efficiency Pt-free electrocatalysts for hydrogen evolution reaction (HER) is a challenging and demanding task nowadays. Herein, graphene wrapped carbon nanofiber @ molybdenum disulfide (GCNF@MoS2) hybrids with hierarchical structure have been successfully prepared as HER electrocatalysts through the combination of electrospinning, solution soaking and solvothermal methods. The wrapping of few-layered graphene functions crucially as a "bridge" closely linking three-dimensional (3D) carbon nanofibers and electrocatalytically active MoS2, providing a highly conductive pathway through the whole hybrids, thus facilitating the transport of electrons. Furthermore, carbon nanofibers acting as "spacers" between graphene layers can efficiently impede their restacking, thus giving full play to the superior electrical conductivity of graphene. Benefiting from the 3D network and template of GCNF, MoS2 nanosheets can grow densely and perpendicularly on the fiber surface, therefore exposing catalytically active edges effectively. Owing to the synergistic effects among three components, the GCNF@MoS2 hybrid exhibits remarkable electrocatalytic activity with a low onset potential of -0.08V, a small Tafel slope of 49.6 mV per decade, a large current density (10.0 mA cm (2) at eta = 0.15 V) as well as excellent stability. Apart from fabricating an efficient HER catalyst, this work also provides a practical strategy for designing hybrid materials with multi-functions for their potential applications in new energy field. (C) 2016 Elsevier Ltd. All rights reserved.