Transition Metal Induced the Contraction of Tungsten Carbide Lattice as Superior Hydrogen Evolution Reaction Catalyst.

Tungsten carbide (WC) materials have exhibited platinum-like catalytic behavior in many fields, whereas the adsorption of pure tungsten carbide for H is too strong and demonstrates low activity for hydrogen evolution reaction (HER). Herein, we successfully introduced transition metal into WC lattice and optimized the electron structure around Fermi level ( EF) of WC via facile annealing CoW-based metal-organic framework precursors. X-ray diffraction, X-ray photoelectron spectroscopy, and X-ray absorption fine structure verified the incorporation of Co and the contraction of WC lattice. Density functional theory calculations indicated that the doping of Co into WC significantly increases the state density of WC at EF derived from the delocalization of Co charge, resulting in the moderate H2O binding energy and weakened H adsorption. As expected, the optimal Co-doping WC (Co/W molar ratio = 3) efficiently catalyzed HER with a low onset potential (31 mV) and a current density of 10 mA cm-2 at a low overpotential of 98 mV in 1.0 M KOH media, which was superior to that of WC/CN and Co/CN. Similarly, Ni and Fe could also modulate the electronic structure of WC and improve the HER activity.