Ruthenium–molybdenum nanoparticles with multi-valence ruthenium species to drive redox electrocatalysis at high current densities

Coupling furfural electrochemical hydrogenation (FEH) with hydrazine oxidation (HzOR) in an electrochemical process offers an effective pathway to obtain high-value products, while simultaneously addressing hydrazine contamination and lowering overall energy consumption. Although Ru has been recognized as an effective bifunctional catalyst toward both FEH and HzOR, challenges remain in achieving large current densities and fully clarifying the underlying activity and mechanism. In this work, a Ru-based device was engineered by introducing Mo dopants to regulate the proportion of Ru 0 and Ru 4+ species, which enabled a remarkable current density of 500 mA cm −2 at 0.31 V. Combined experimental and theoretical investigations demonstrate that Ru 0 sites enhance water dissociation to generate active hydrogen for subsequent hydrogenation, while Ru 4+ sites stabilize the (C 4 H 3 O)CH 2 O* intermediate during FEH. For HzOR, Ru 4+ lowers the barrier of the rate-determining step, thus accelerating the overall process, whereas Ru 0 facilitates dehydrogenation and the release of N 2 . Notably, the integrated FEH–HzOR system dramatically reduces the electricity demand for converting furfural to furfuryl alcohol, requiring only 32,711 kWh per ton of FA, which corresponds to a 69.5 % energy saving compared with conventional FEH (97,766 kWh per ton).