Synergistic Ru-Ni-Cu interface for stable hydrogen evolution on 1% Ru-Ni@Cu alloy grown directly on carbon paper electrode

A Ru-Ni@Cu alloy catalyst with a well-connected two-phase or three-phase contact interface is fabricated as an alternative to a Pt-based catalyst for the hydrogen evolution reaction (HER) in water electrolysis in this study. For optimum bonding and adhesion stability, the alloy particles are grown directly on carbon paper (CP) by the hydrothermal method. The alloy particles are composed of central Cu cores, Ni nests wrapped around Cu core, and small (2.0 nm) Ru nanoparticles embedded at the Ni nests. The Ni surface readily adsorbs water, the high conductivity of Cu increases the electron density of the electrode surface to facilitate water splitting, and the Ru surface adsorbs more H+ ions, thus promoting hydrogen production in the Ru-Ni@Cu alloy. Eventually, despite the use of only 1.0 wt% Ru, the 1% Ru-Ni@Cu/CP electrode exhibits a low overpotential of −0.15 V (η = 246 mV and 87.08 mV dec−1) at 100 mA cm−2 in a 1.0 M KOH electrolyte, similarly to the −0.1 V overpotential of the 100% Pt/CP electrode. The electrode maintains excellent catalytic activity without deterioration for 10 days with a Faraday efficiency of 96.89% (50 h) HER and 3000th LSV cycles. [Display omitted] •Ru-Ni@Cu alloy with three-phase interface grown directly onto CP.•Cu core in the center, Ni nest on the outside, and 2.0 nm-sized Ru particle between Cu and Ni.•Hydrogen production promoted by more H+ ions adsorption on the Ru surface.•A low overpotential of −0.15 V even though only 1.0 wt.-% Ru usage.•Faraday efficiency of 96.89% for 3000 min-HER, without catalytic deactivation for 10 days.