Enhanced hydrogen evolution performance by nanoarchitectonics of Fe/Co alloy electrode beyond Fe/Co/Ni alloy electrode

Abstract

With the increasing global energy demand, hydrogen production from electrolytic water became the main way to prepare efficient and clean hydrogen energy. Transition metal catalyst were promising hydrogen evolution catalyst for low cost, stable performance and high catalytic activity. In this study, Fe–Co–Ni, Co–Fe, Ni–Fe and Co–Ni alloy electrodes were prepared by electrodeposition. Among the four alloys, Co–Fe showed the best hydrogen evolution performance. The surface of Co–Fe alloy electrode coating was composed of round small particles of different sizes closely combined to form a large complex. In the alloy, Co was accounted for 62.2% and Fe was accounted for 37.8%. The increase of Co content increased the specific surface area of the electrode, provided a large number of catalytic active sites, and improved the hydrogen evolution performance. In the Co–Fe alloy electrode, Fe was existed in the form of Fe2+ and Fe3+, Co was existed in the form of Co2+. The electrochemical test results showed that Co–Fe alloy electrode had the highest electrocatalytic activity. Since the conductivity of cobalt hydroxide and iron hydroxide generated in the strong alkali environment, which was stronger than that of nickel hydroxide, the internal resistance of the Co–Fe alloy electrode in the hydrogen evolution process was reduced. Under the same conditions, the Co–Fe alloy electrode needed only 1483 mV overpotential to drive a current density of 0.1 A/cm2. The Tafel slope of Co–Fe alloy electrode was the smallest, only 144.04 mV/dec, and the electron transmission efficiency was the highest. Co–Fe alloy electrode had the lower electron conduction resistance and better electrochemical hydrogen evolution performance.