The influence of molybdenum and silicon on activity of Ni+W composite coatings in the hydrogen evolution reaction

Ni + W, Ni + W + Si and Ni + W + Mo + Si composite coatings were obtained by electrolytic codeposition of crystalline nickel from an electrolyte containing suspension of W, Mo and Si powders. These coatings were obtained under galvanostatic conditions, at the current density of j(dep.) = 0.100 A cm (- 2) and at the temperature of 338 K. Chemical composition of obtained coatings was determined by energy dispersive X-ray spectroscopy (EDS) method. The electrochemical activity of these coatings was studied in the process of hydrogen evolution reaction (HER) from 5 M KOH solution using steady-state polarisation and electrochemical impedance spectroscopy (EIS) methods. On the basis of the results of EIS measurements, the rate constants of the HER as well as the surface roughness factor were determined. It was found that Ni + W + Mo + Si composite coatings are characterised by enhanced electrochemical activity toward hydrogen evolution as compared with Ni + W + Si and Ni + W coatings. The reason for this is connected with the presence of additional composite components (W, Mo, Si). Thus, obtained coatings may be useful in application as electrode materials for the hydrogen evolution reaction. Copyright (c) 2008 John Wiley & Sons, Ltd.