Electrodeposited Ni-Fe-C Cathodes for Hydrogen Evolution

Abstract

Tailoring of active nickel alloy cathodes for hydrogen evolution in a hot concentrated hydroxide solution was attempted by electrodeposition. Electrodeposited iron is naturally more active for hydrogen evolution than nickel, but Ni-Fe alloys show further high activity for hydrogen evolution, although the rate-determining step being assumed as proton discharge is not changed. The carbon addition to iron or nickel remarkably enhances the activity for hydrogen evolution and changes the mechanism of hydrogen evolution. Ternary Ni-Fe-C alloys show the highest activity for hydrogen evolution, and the Tafel slope of hydrogen evolution is about 33 mV/dec, suggesting the rate-determining step of desorption of adsorbed hydrogen by recombination. XPS analysis reveals that the charge transfer occurs from nickel to iron in alloys and the carbon addition particularly enhances the charge transfer. Accelerated proton discharge due to enhanced charge transfer from nickel to iron seems responsible for the high activity of the Ni-Fe-C alloys for hydrogen evolution.

Electrodeposited Co-Fe and Co-Fe-C Alloys for Hydrogen Evolution in a Hot 8 kmol m<SUP>-3</SUP> NaOH Solution

“…It has been known 13,14) that the carbon addition to the NiFe alloys prevents iron dissolution from Ni-Fe-C alloys during open circuit immersion in 8 kmol m À3 NaOH at 363 K. Nevertheless, in the present study, the carbon addition is not effective in preventing dealloying degradation due to preferential dissolution of iron from the Co-Fe-C alloys during open circuit immersion in the hot alkaline solution.…”

“…As has been found for Ni-Mo-O 11,12) and Ni-Fe-C 13,14) alloys, the additions of electronegative elements such as oxygen and carbon are quite effective in preventing the preferential dissolution of molybdenum and iron.…”

“…Enhancement of cathodic activity of nickel for electrolytic hydrogen evolution has been carried out by the formation of nickel alloys such as Ni-S, 1) Raney Ni, 2) Ni-Mo, [3][4][5][6][7][8] Raney Ni-RuO, 2,9) Ni-Sn, 10) Ni-Mo-O 11,12) and Ni-Fe-C. 13,14) Among them, electrodeposited Ni-Fe-C alloys showed the highest activity for hydrogen evolution in hot alkaline solutions and excellent durability: The overpotential for hydrogen evolution at the current density of 1000 Am À2 in 8 kmol m À3 NaOH at 363 K was less than 100 mV. The activity did not decrease and no iron dissolution occurred during open circuit immersion in the hot alkaline solution.…”

Electrodeposition of Electroactive Co–B and Co–B–C Alloys for Water Splitting Process in 8 M NaOH Solutions

“…It means transfer of the charge from carbon to metal in alloy and causes a faster transfer of the charge from metal to the hydrogen atom and thus acceleration of the hydrogen evolution process on such an alloy. This phenomenon also takes place in the case of alloys Ni-Mo-C, Co-W-C, and Ni-Fe-C [21][22][23][24]. Combining nickel, molybdenum or cobalt, and non-metals into semiconducting compounds Ni-S [25], CoSe [26], Mo-Se [26,27], and Mo-S [28] has been intensely investigated recently.…”

Studies on the Different Type of Catalysts on Aqueous Electrolysis as Well as Membrane Water Splitting for Production of Hydrogen

“…To decrease the activation overvoltage, number of electrocatalysts have been investigated and extensively reviewed. Among these, transition metal oxides and transition metals alloys have been considered most promising for O 2 evolution and H 2 evolution electrode catalysts, respectively [1][2][3]. Any suspended particle capable of conducting current may act as microelectrode in a close proximity to the macroelectrode.…”