▎ 摘　　要

Designing highly efficient and stable electrocatalysts for hydrogen evolution reaction (HER) is critical to the large-scale application of clean hydrogen energy. Herein, NiFe@N-doped graphene microtube (NiFe-NGMT) composites have been synthesized by a facile metal organic framework (MOF) precursor route, and employed as an effective electrocatalyst for HER. The NiFe-NGMT composites, which consist of NiFe alloy particles enveloped in N-doped graphene microtubes with a diameter of 1-2 mu m, were synthesized by thermal annealing a MOF precursor of nickel nitroprussides (NiFe(CN)(5)NO center dot 2H(2)O) in nitrogen atmosphere. By adjusting the pyrolysis temperature, the diameter of the tubular graphene can be tuned to 50 -200 nm. The obtained NiFe-NGMT composites exhibit excellent catalytic activity for HER with a low overpotential (70.5 mV) and a small Tafel slope (63.4 mV per decade), which afford the materials promising application for splitting water to generate hydrogen. (C) 2017 Elsevier Ltd. All rights reserved.