Bell-shaped RuFe/Ni5P4 for efficient urea-assisted electrolytic hydrogen production

Abstract

Urea-assisted electrolytic hydrogen production requires much lower theoretical cell voltage than the conventional water splitting technology (E^θ = 0.37 V vs. 1.23 V), serving as a promising alternative for concepts of “clean energy” and “cleaning pollutant”. However, screening highly robust catalysts with industrial-level current density (>200 mA cm⁻²) is still challenging. To overcome this challenge, bell-shaped RuFe/Ni₅P₄ catalysts grown on nickel foam (NF) were developed via dual doping of Fe and Ru and a facile phosphidation process. The unique bell-shaped structure significantly contributes to the improved contact with the electrolyte, leading to the promoted mass transfer as well as the efficient release of CO₂ and N₂ bubbles generated during the urea oxidation reaction (UOR). Moreover, the strong electronic interaction between Ru and Ni₅P₄ ensures high UOR activity with a high current density of 600 mA cm⁻² at 1.45 V (vs. RHE). Moreover, an assembled Ru/NF|KOH, CO(NH₂)₂|RuFe/Ni₅P₄ electrolytic cell demonstrated a highly efficient hydrogen production rate in order to reach a current density of 600 mA cm⁻² at a low overall voltage of 1.55 V. This superior performance substantially satisfies the industrial requirement and paves the way to an efficient catalyst design for the UOR and green hydrogen production.