Earth-abundant Ni has emerged as an interesting catalytic material toward electrochemical hydrogen evolution reaction (HER) in alkaline media, but developing high-performance Ni-integrated HER catalysts is still a big challenge. Herein, we describe the development of self-standing Ni-tungsten nitride heterostructure nanowires array on conductive carbon cloth (Ni-WN/CC) as a highly efficient 3D hydrogen-evolving cathode in 1.0 M KOH with catalytic activity outperforming most reported Pt-free HER catalysts. This Ni-WN/CC electrode exhibits a negligible onset overpotential and a Tafel slope of 71 mV dec(-1). It demands overpotentials of only 47, 70, and 155 mV to drive 10, 20, and 100 mA cm(-2), respectively, with its activity being maintained for 10 h. Such high hydrogen evolution activities are due to electrocatalytic synergistic effects of Ni and WN. (C) 2016 Elsevier Ltd. All rights reserved.