SORPTION OF HYDROGEN AND KINETICS OF HYDROGEN EVOLUTION ON AMORPHOUS NI-SX ELECTRODES

Electrolytically prepared Ni-S(x) layers with a sulphur content ranging between 10 and 20 wt% have a higher activity for the hydrogen evolution reaction (HER) (j(o) congruent-to 2.5-35 x 10(-5) A cm-2) in comparison with nickel electrodes (j(o) congruent-to 1.5 x 10(-5) A cm-2). Ni-S(x) electrodes sorb high amounts of hydrogen. The greater part of this hydrogen is present in the absorbed hydride form. The thermal treatment of electrodeposited layers (1-4 h at 150-degrees-C) causes the decrease in the rate of HER by approximately one order of magnitude and, simultaneously, the decrease in hydrogen sorption. X-ray diffraction analysis showed that Ni-S(x) layers are originally amorphous but become crystalline after a thermal treatment.