Photocatalytic selective oxidation of biomass-derived 5-hydroxymethylfurfural to 2,5-diformylfuran on WO3/g-C3N4 composite under irradiation of visible light

WO3/g-C3N4 (graphitic carbon nitride) composite was prepared via a directly calcination method with ammonium tungstate hydrate and melamine as raw materials, and applied in the photocatalytic oxidation of 5-hydroxymethylfurfural (5-HMF) to 2,5-diformylfuran (DFF) for the first time. Its physicochemical properties were characterized by HR(TEM), XRD, FT-IR, XP, UV-vis, PL, PC and EIS methods. The results revealed that the doping of WO3 into g-C3N4 can reduce the possibility of charge recombination and thus enhancing the photocatalytic activity. The impact factor, such as incident wavelength, reaction time, and solvent were also studied on the photocatalytic behavior. 4.7%WO3/g-C3N4 composite catalyst exhibits the highest 5-HMF conversion of 27.4% with DFF selectivity of 87.2% under the irradiation of visible-light (>400 nm). As the active species, O2− and h+ plays an important role to convert 5-HMF to DFF. Finally, the Z-scheme mechanism and reaction route were proposed by combining the photocatalytic performance with the active oxygen species research of the WO3/g-C3N4 catalyst.