Realization of electron-deficient Ru sites via Co4N coupling for synergistically enhanced alkaline hydrogen evolution

Abstract

Ruthenium (Ru), benefitting from efficient water dissociation ability, is considered a good candidate for alkaline hydrogen evolution reaction (HER); however, the strong binding of H intermediates over Ru sites leads to a limited desorption behavior and thus an unsatisfactory HER activity. Here, we propose a strategy to fabricate a well-defined hetero-interface via anchoring Ru nanoparticles on Co₄N nanorods grown on nickel foam (Ru/Co₄N/NF). The as-prepared Ru/Co₄N/NF catalyst is demonstrated to effectively catalyze water splitting into hydrogen in an alkaline electrolyte, with an overpotential of 145 mV to reach 100 mA cm⁻² and a Tafel slope of 25 mV dec⁻¹, far surpassing bare Ru/NF and Co₄N/NF. Experimental observations combined with computational simulations reveal that the charge migration from Ru to Co₄N contributes to the formation of electron-deficient Ru sites and shifts the d-band center away from the Fermi level, which is conducive to hydrogen desorption. Meanwhile, the electron coupling effect between Ru and Co₄N reduces the H₂O adsorption energy and allows more electrons to participate in H₂O molecule activation.