Spatially isolated single-site VO_x on activated carbon for efficient oxidation of carbohydrates to formic acid

Vanadium-based catalysts are widely used in the oxidation of carbohydrates to produce formic acid (FA), a promising liquid organic hydrogen carrier, but still suffers from low yield due to the formation of CO₂. This study found that the spatially isolated VO_x on active carbon (AC) can significantly increase FA yield from 43.5 to 72.9% in glucose oxidation compared with free VO_x. Two specific roles of AC were revealed. Firstly, the oxygenated functional groups, high surface area and abundant microporous of AC, play a crucial role in the atomic dispersion of VO_x, resulting in a heterogeneous, single-site VO_x-AC catalyst. The isolated VO_x site favors the oxidative C–C bond cleavage in glucose via a stepwise α-cleavage pathway, thus improving FA selectivity. Secondly, the conductive AC acts as an electron buffer, which accelerates the catalytic redox cycle between V⁵⁺ and V⁴⁺ of the isolated VO_x sites, thus increasing the reaction activity. The prepared single-site VO_x-AC catalyst is reusable and can generate a concentrated FA solution (4.7 wt%) by simple filtration of the solid catalyst. This work presents a simple method for the production of H2 energy carrier from biomass and provides a fundamental basis for designing efficient catalytic systems for aqueous-phase oxidation reactions. © 2026 Elsevier B.V.