Highly selective photocatalytic oxidation of biomass-derived chemicals to carboxyl compounds over Au/TiO2†
Highly selective transformation of biomass-derived chemicals into value-added chemicals is of great importance. In this work, selective photooxidation of various biomass-derived chemicals, including ethanol, glucose, xylose, 2-furaldehyde, 5-hydroxymethyl-2-furfural, and furfuralcohol to the corresponding carboxyl compounds was studied using atmospheric air as the oxidant at ambient temperature. It was found that the reactions could be carried out efficiently over Au nanoparticles (AuNPs) supported on TiO2 (AuNPs/TiO2) under both ultraviolet (UV) and visible light in Na2CO3 aqueous solution. Under the optimized conditions, the selectivities for desired products were higher than 95% for all the reactions. Detailed studies indicated that the surface plasmon resonance of AuNPs and the band-gap photoexcitation of TiO2 were responsible for visible-light-responding and UV-light-responding activities, respectively. Na2CO3 acted as the promoter for the visible-light-induced oxidation and the inhibitor of reactive oxygen species with strong oxidation power under UV light.