Carbon support enhanced metal - support interaction enabling higher concentration furfural hydrogenation at constant current conditions.

The electrochemical reduction of furfural (FF) offers a sustainable approach for producing value-added furfural alcohol (FA). Nevertheless, the limited adsorbed hydrogen (*H) generation capacity on Cu cathode restricts the reaction performance. Because the competitive adsorption of FF and *H decreases *H coverage and induces severe dimerization, most prior studies employed low FF concentrations (typically 20 mM) under constant potential conditions. In this work, carbon-supported Cu nanoparticles grown on Cu nanowire arrays (defined as Cu@Cu/C) were combined with constant current electrolysis for high-concentration FF reduction. A high Faradaic efficiency (72.9 %) and production rate (0.14 mmol cm h) of FA were realized at -10 mA cm, with a conversion of 98.1 %. Both the Faradaic efficiency and production rate can be sustained with gradual increases in current density or adjustments of FF concentration within a certain range, showing substantial enhancement relative to Cu-nano. Compared with pure Cu-nano, the favorable interaction between Cu nanoparticles and carbon support was certified to regulate the adsorption configuration and strength of FF, and enhance the *H generation performance, which optimizes the *H coverage at cathodic surface and promotes FF hydrogenation with *H via an electrocatalytic hydrogenation (ECH) mechanism. Overall, this work provides a simple and feasible strategy to promote interfacial *H, thus enhancing higher concentration hydrogenation of FF to FA by constant current electrolysis over Cu-based cathode.