Oxygen vacancies enhance non-Faradaic deprotonation in furfural electro-oxidation

Electrochemical oxidation of biomass-derived furfural enables simultaneous production of furoic acid and hydrogen evolution, providing a sustainable strategy for integrated chemical synthesis and clean energy generation. However, its efficiency is limited by a non-Faradaic deprotonation process, which requires hydroxide (OH⁻) participation, as these ions become depleted at the catalyst interface under high reaction rates. Herein, we introduce oxygen vacancy (V O )-rich copper catalysts that enhance local OH⁻ concentration and accelerate key deprotonation steps. Theoretical simulations reveal that enhance the local OH⁻ concentration and accelerate the key deprotonation steps. Theoretical simulations reveal that high OH⁻ coverage lowers the energy barrier for gem-diolate anion (GDA) formation, and V Os increase the interfacial OH⁻ concentration by 1.76-fold at 100 mA cm −2 . Guided by these insights, we synthesized the Cu nanowires with tunable V O densities via controlled reduction. The V O-rich Cu catalyst achieves a current density of 208.1 mA cm −2 at 0.5 V vs. RHE, 4.8 times higher than V O-poor Cu, while maintaining a furoic acid Faradaic Efficiency of 99 %. Operando infrared spectroscopy confirms that V Os facilitate OH⁻ enrichment and enable efficient adsorption of FF on Cu 0 /Cu + active sites, synergistically promoting GDA formation and accelerating C–H bond cleavage. When integrated into a flow reactor, the V O-rich Cu enables bipolar hydrogen production at a cell voltage of just 0.25 V, compared to 1.73 V for water splitting, achieving an 85 % reduction in energy input. These findings establish V O engineering as an effective strategy for advancing biomass electrooxidation and low-voltage hydrogen generation. Oxygen vacancy (V O )-rich copper catalysts significantly enhance the electrochemical conversion of biomass-derived furfural to furoic acid by increasing local hydroxide ion concentration at the catalyst interface. The V O -rich Cu catalyst achieved a current density of 208.1 mA cm⁻ 2 (4.8 times higher than V O -poor Cu) while maintaining 99 % furoic acid efficiency, and enabled hydrogen production in a flow reactor at just 0.25 V compared to 1.73 V for conventional water splitting. • V O-rich Cu boosts OH⁻ enrichment, speeding FOR deprotonation process. • The V O-rich Cu catalyst achieves a FE FA of 99 % at 208.1 mA cm⁻ 2 , 4.8 times higher than V O-poor Cu. • V O-rich Cu enables bipolar H 2 production with 85 % energy reduction compared to conventional water splitting.