Synthesis, characterization and photocatalytic properties of PDI/TiO 2 /activated carbon nanocomposite

1-Hydroxy perylene diimide-doped TiO 2 loaded on the activated carbon (HO-PDI/TiO 2 /AC) nanocomposite was prepared by hydrothermal method. The nanocomposite was characterized by X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, BET surface area, UV–Vis diffuse reflectance spectroscopy, and photoluminescence spectroscopy. The photocatalytic activity of the nanocomposite was investigated by degradation of AMX and EBT under visible light irradiation. The results indicated that the photocatalytic activity of the TiO 2 increased under visible light irradiation in the presence of the HO-PDI and activated carbon. AC could disperse the HO-PDI/TiO 2 nanoparticles and inhibit their agglomeration to improve the photoreactivity, while HO-PDI could be excited to generate electrons and holes under visible-light illumination. Photogenerated holes in TiO 2 could be captured by AC, and the holes can be easily moved to the surface of AC, directly initiating the photocatalytic reaction. Based on these results, a dual catalytic mechanism of AC-TiO 2 involving dye sensitization and electron–hole separation was proposed. Graphic abstract