Abstract: Nano-crystalline tungsten carbide thin films were fabricated on foam nickel and nickel foil substrates by plasma enhanced chemical vapor deposition. The structure and morphology and constitutes of the thin films were token by XRD, SEM, EDS. The real surface area, chemistry stability and electro-catalytic properties for the hydrogen evolution reaction of the films were also investigated. The electrochemical analysis shows that the real surface area of 1cm² WC/foam-Ni and WC/Ni films catalysts is 83.21 and 64.13cm² respectively. The Tafel
parameter a of the thin film electrode for hydrogen evolution is 0.422～0.452V.
The hydrogen evolution exchange current density is 4.02～4.22×10^-4A/cm², When the over-potential is 263mV, the activation energy of hydrogen evolution is 45.62～45.77kJ/mol.

Key words: PECVD, nano-crystalline tungsten carbide thin film, electrocatalysis, hydrogen evolution