Selective Oxidation of 5-Hydroxymethylfurfural to 2,5-Diformylfuran Using Cadmium Sulfide Quantum Dots

Cadmium sulfide quantum dots (CdS QDs) photocatalysts were prepared by the hydrothermal method, and 5-hydroxymethylfurfural (HMF) was catalyzed to 2,5-diformylfuran (DFF) under light irradiation, with fewer by-products and a selectivity of 95.74%. In the process of photocatalytic oxidation of HMF, the selectivity of DFF was higher when acetonitrile was used as the reaction solvent, which was more conducive to the production of DFF. Meanwhile, the conversion rate of HMF improved with the increase in reaction time. However, the selectivity of DFF decreased when the reaction time exceeded 10 h. Under the optimal reaction conditions, the conversion of HMF, the yield and the selectivity of 2,5-diformylfuran showed the best photocatalytic effect, which were 42.57, 40.64, and 95.47%, respectively. It was found out that superoxide radical was the main active species involved in the photocatalytic reaction, while the photogenic hole was the secondary active species. Further, the mechanism of the photocatalytic reaction was deduced.