Electrodeposited Co-Ni-Fe-C alloys for hydrogen evolution in a hot 8 kmol·m-3 NaOH

Abstract

Active cobalt alloy cathodes for hydrogen evolution in 8 kmol·m -3 NaOH at 90°C was tailored by electrodeposition. Enhancement of cathodic activity of Co-Ni alloys was carried out by the formation of Co-Ni-Fe-C alloys. The addition of both iron and carbon was effective in enhancing the electrolytic hydrogen evolution activity, and the carbon addition was further effective in preventing preferential dissolution of iron and cobalt, that is, dealloying corrosion during shutdown period in the hot concentrated alkaline solution. The fee Co-Ni-Fe-C alloys with about 15 at% iron showed the best performance with high hydrogen evolution activity and durability without dealloying corrosion. The alloys with high iron contents forming the bcc structure and showing sufficiently high activity without carbon addition suffered readily dealloying corrosion, and complete prevention of dealloying of the high iron alloys was not achieved by carbon addition. © 2006 The Japan Institute of Metals.