Electrocatalytic properties of new electrocatalysts for hydrogen evolution in alkaline water electrolysis

New electrocatalysts consisting of hydrogen storage alloys, such as MmNi(3.6)Co(0.75)Mn(0.4)Al(0.27) alloy (Mm = misch metal), LaNi4.9Si0.1 alloy and Ti2Ni alloy and nickel-molybdenum coatings were prepared. Their electrocatalytic activity for hydrogen evolution and their time stability were investigated in 30 wt% KOH at 70 degrees C. The surface morphology and chemical composition of these electrodes were also examined before and after electrolysis. The results show that the activity for hydrogen evolution increases with increase in molybdenum content and is dominated by electrode surface composition. The hydrogen storage alloys inside the electrodes mainly serve the functions of enhancing corrosion-resistance against power interruptions through electrochemically releasing absorbed hydrogen. These electrocatalysts not only have a low hydrogen overpotential, but also excellent time stability under both conditions of continuous and intermittent electrolysis. (C) 1999 International Association for Hydrogen Energy. Published by Elsevier Science Ltd. All rights reserved.