HYDROGEN EVOLUTION CATHODES WITH AB5-CATALYZED COATINGS

AB5-catalyzed hydrogen evolution cathodes were made with coatings containing particles of AB5 and nickel, plus an inert binder. The effects of coating composition and catalyst particle size on hydrogen evolution were determined. Raising the binder content of the cathode coating increased the overpotential due to catalyst masking, as confirmed by scanning electron microscopy. Replacing half of the AB5 in the coating with nickel, which is much less catalytically active for the hydrogen evolution reaction, had a relatively small effect on the overall cathode efficiency. Reducing th AB5 particle size to increase surface area reduced the overpotential slightly. The AB5-catalyzed cathodes showed stable overpotentials during electrolyses of up to 7000 hours, and were not adversely affected by extended open circuit exposure or reverse polarity tests.