Electrodeposited Co-Fe and Co-Fe-C Alloys for Hydrogen Evolution in a Hot 8 kmol m^-3 NaOH Solution

Abstract

Tailoring of active cobalt alloy cathodes for hydrogen evolution in a hot concentrated sodium hydroxide solution was attempted by electrodeposition. Enhancement of cathodic activity of cobalt for electrolytic hydrogen evolution has been carried out by the formation of Co-Fe and Co-Fe-C alloys containing different content of iron. The carbon addition to Co-Fe alloys was made to enhance the electrolytic hydrogen evolution activity and to prevent open circuit corrosion in 8 kmol m⁻³ NaOH at 363 K. The best condition for electrodeposition of Co-Fe alloy was pH 4 and the iron sulfate concentration of more than 5 kg m⁻³. Under this condition the alloy was obtained with nanocrystalline bcc phase as a dominant and with the highest hydrogen evolution activity. The carbon addition slowed down preferential iron dissolution by open circuit corrosion in the hot alkaline solution but was not effective in complete prevention of the open circuit corrosion and in enhancing the hydrogen evolution.