Furthermore, the one-dimensional (1D) nanowire morphology and graphite-like carbon shells also promote the conductivity of the whole electrocatalytic material. DFT calculations and experimental results demonstrate that such prominent performance towards the HER was mainly attributed to abundant interfaces between WC and W 2C phases in the cable-like heterojunction nanowires which may exert both the high HER activity of W 2C and the excellent electrochemical stability and conductivity of WC. With the optimized phase composition, WC/W NWs (WC : W 2C ≈ 1 : 1.3) display the low overpotentials of 69 mV and 56 mV at the cathodic current density of 10 mA cm −2 and small Tafel slopes of 52 and 59 mV dec −1 in 0.5 M H 2SO 4 and 1 M KOH, respectively. Herein, ultrafine cable-like WC/W 2C heterojunction nanowires (NWs) covered by few-layer N-doped graphite-like carbon (labeled WC/W NWs) have been firstly accomplished via a simple two-step pyrolysis treatment of W 18O 49 NWs precursor, exhibiting tunable phase composition, excellent HER activity, fast kinetic metrics and remarkable stability along the entire pH range. Developing highly active, durable and economical noble-metal-free electrocatalysts for the hydrogen evolution reaction (HER) plays a crucial role in the future hydrogen economy.
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