HYDROGEN EVOLUTION ON ELECTRODEPOSITED NICKEL COBALT MOLYBDENUM IN ALKALINE WATER ELECTROLYSIS

The hydrogen evolution reaction (HER) was conducted on nickel-cobalt-m olybdenum electrodes in a 30 wt% KOH solution at temperatures from 298 to 353 K. These nickel- and cobalt-based ternary materials were elect rodeposited on a stainless steel screen, initially at a current densit y of 0.5 A cm-2 and subsequently at 2 A cm-2. They showed good adhesio n to the substrate, high surface roughness and they enhanced the HER i n water electrolysis compared with nickel, cobalt, nickel-molybdenum a nd cobalt-molybdenum deposited electrodes, having comparable or even h igher deposit loadings. The HER enhancement on the ternary materials w ith respect to nickel-molybdenum and cobalt-molybdenum was attributabl e to their large surface area. On the ternary materials, two Tafel slo pes were distinguished on the HER polarization in the low and high HER overpotential ranges. However, no conventionally proposed relation be tween Tafel slope and temperature was found; the transfer coefficient increased with temperature under the experimental conditions.