Selective oxidation of 5-hydroxymethylfurfural to furan-2,5-dicarbaldehyde using chitosan-based biochar composite cadmium sulfide quantum dots

In the present study, a self-doped N-doped chitosan carbon (Ch) was prepared by activated carbonization as a carrier. A series of CdS QDs/xCh composite photocatalysts were synthesized by hydrothermal method to support CdS QDs with different contents. Catalytic oxidation of 5-hydroxymethyl furfural (HMF) was performed to produce 2,5-diformyl furan (DFF). Results showed that 20% Ch loading (CC-20), 10 h reaction time, and 1/4 raw material/catalyst ratio, HMF conversion rate of 78.73% and DFF selectivity of 97.31% were achieved. Through 5 cycles of experiments on CC-20, results showed less than 10% reduction in photocatalytic degradation rate of CC-20 composite photocatalyst, which confirms good stability and cyclability of the catalyst. Finally, through a series of characterization, the structure, composition, morphology, and photoresponse properties of the composite photocatalyst were investigated; at the same time, the mechanism and conversion path of CdS QDs/Ch photocatalyst were explored.