Ultrahigh length-to-diameter ratio nickel phosphide nanowires as pH-wide electrocatalyst for efficient hydrogen evolution

The hydrogen evolution reaction (HER) represents one promising solution for energy and environmental sustainability. Nickel phosphide with various morphology has been recently investigated as promising earth abundant electrocatalysts for HER. Compared with three or two dimensional morphology, one dimensional (1D) nickel phosphide could provide larger specific surface area and hence improves the HER electrocatalytic performance. However, most reported 1D nickel phosphides show a small length-to-diameter ratio (less than 50). Herein, ultrahigh length-to-diameter ratio Ni2P nanowires synthesized by one-step phosphorization-sulfuration treatment are reported for the first time. The as-prepared nanowires have extremely high length to diameter ratio which ranges from 500 to 1000. The formation mechanism of such morphology is illustrated by a systematic study of the morphology, microstructure and elementary distribution of the nanowire array cathode. The ultralong nanowire morphology clearly helps improve the HER performances, since the self-supported Ni2P nanowire array cathode exhibits outstanding HER electrocatalytic activity and long-term durability in all of the acidic, alkaline, and neutral conditions. (C) 2018 Elsevier Ltd. All rights reserved.