Electrocatalytic Hydrogenation of 5-Hydroxymethylfurfural Promoted by a Ru₁Cu Single-Atom Alloy Catalyst

Electrochemical reduction of biomass-derived 5-hydroxymethylfurfural (HMF) represents an elegant route toward sustainable value-added chemicals production that circumvents the use of fossil fuel and hydrogen. However, the reaction efficiency is hampered by the high voltage and low activity of electrodes (Cu, Bi, Pb). Herein, we report a Ru₁Cu single-atom alloy (SAA) catalyst with isolated Ru atoms on Cu nanowires that exhibits an electrochemical reduction of HMF to 2,5-dihydroxymethylfuran (DHMF) with promoted productivity (0.47 vs. 0.08 mmol cm⁻² h⁻¹) and faradic efficiency (FE) (85.6 vs. 71.3 %) at −0.3 V (vs. RHE) compared with Cu counterpart. More importantly, the FE (87.5 %) is largely retained at high HMF concentration (100 mM). Kinetic studies by using combined electrochemical techniques suggest disparate mechanisms over Ru₁Cu and Cu, revealing that single-atom Ru promotes the dissociation of water to produce H* species that effectively react with HMF via an electrocatalytic hydrogenation (ECH) mechanism.