Structures and electrochemical properties of amorphous nickel sulphur coatings electrodeposited on the nickel foam substrate as hydrogen evolution reaction cathodes

Nickel sulphur coating electrodes were prepared on the nickel foam substrates by electrodeposition method. Morphologies of various layers of nickel sulphur coatings were investigated by SEM. Distributions and mass contents of sulphur were measured by EDX. The phase constitutions of nickel sulphur coatings on the first layer were determined by XRD. Results indicated that distributions of sulphur contents in various layers of nickel foam substrates are not homogeneous but gradient, the particle sizes in various layers are not the same. The amorphous structure of the nickel sulphur coating depends on the current density and sulphur content in the coatings. When the mass contents of sulphur in the coatings change from 18% to 18.62% the HER potentials are lowest. Large amount of adsorbed H atoms in amorphous Ni-S coating in the course of electrolysis in alkaline media will improve the electrocatalytic property of HER significantly. The active amorphous Ni-S coating begins to dissolve at potential -0.6 V and begin to be passivated at potential -0.47 V. Among the studied nickel sulphur coating electrodes, HER potentials of the coatings electrodeposited on the nickel foam substrate are lowest. The apparent activation energy is 46.8 kJ mol(-1) at 0.1 V HER over-potential. At 85 degrees C, the stimulant cell potentials are 1.7 V at 0.2 A cm(-2) and 1.96 V at 0.4 A cm(-2). (c) 2006 Elsevier B.V. All rights reserved.