Decoupling C–H Activation and Overoxidation via Partially Oxidized Clusters for Electrooxidation of Tetrahydrofurfuryl Alcohol to Tetrahydrofuroic Acid

Abstract Selective electrooxidation of biomass-derived tetrahydrofurfuryl alcohol (THFA) to tetrahydrofuroic acid (THFCA) is a highly valuable pathway for sustainable chemical synthesis, which is fundamentally constrained by a paradoxical relationship: Facile C–H bond activation is coupled with sluggish desorption of the product. Herein, a partially oxidized cluster anchored on a TiO2 nanosheet (Ru–Ru(O) Cluster/TiO2) is developed to circumvent the contradiction through precise coordination engineering. X-ray absorption fine structure spectroscopy reveals unique Ru–Ru(O) clusters featuring concurrent Ru–Ru and Ru–O coordination, resulting in electronic properties distinct from both single-atom and nanoparticle regimes. Density functional theory calculations and in situ attenuated total reflection surface-enhanced infrared absorption spectroscopy reveal that the coordination-unsaturated Ru–O bonds and the moderate Ru 4d-band center facilitate facile THFA activation, while the electron-rich Ru centers modulated by Ru–Ru bonds promote the timely desorption of THFCA, thereby decoupling the contradiction between THFA reactivity and THFCA selectivity. As a result, the Ru–Ru(O) Cluster/TiO2 achieves a superior THFA-to-THFCA current density of 65 mA cm–2 with 85% THFCA selectivity at 1.9 V vs RHE. An anion exchange membrane flow electrolyzer equipped with the Ru–Ru(O) Cluster/TiO2 catalyst achieves a high current of 300 mA at 2.25 V and steadily operates for 75 h. Techno-economic analysis demonstrates that the scaled-up Ru–Ru(O) Cluster/TiO2 electrocatalytic process achieves a low total production cost of 6.79 USD kg–1, representing a 72% cost saving over conventional thermocatalytic routes and highlighting its potential for industrial application.