Hydrogen evolution on electrodeposited nickel-cobalt-molybdenum in alkaline water electrolysis

The hydrogen evolution reaction (HER) was conducted on nickel-cobalt-molybdenum electrodes in a 30 wt% KOH solution at temperatures from 298 to 353 K. These nickel- and cobalt-based ternary materials were electrodeposited on a stainless steel screen, initially at a current density of 0.5 A cm −2 and subsequently at 2 A cm −2. They showed good adhesion to the substrate, high surface roughness and they enhanced the HER in water electrolyssi compared with nickel, cobalt, nickel-molybdenum and cobalt-molybdenum deposited electrodes, having comparable or even higher deposit loadings. The HER enhancement on the ternary materials with respect to nickel-molybdenum and cobalt-molybdenum was attributable to their large surface area. On the ternary materials, two Tafel slopes were distinguished on the HER polarization in the low and high HER overpotential ranges. However, no conventionally proposed relation between TAfel slope and temperature was found; the transfer coefficient increased with temperature under the experimental conditions.