Sulfur-doped polyimide photocatalyst with enhanced photocatalytic activity under visible light irradiation

Sulfur-doped polyimide (SPI) photocatalysts were synthesized for the first time via an in situ thermal copolymerization method using sublimed sulfur (S4) as a dopant. Sulfur doping not only extended the absorption range of polyimide (PI) for visible light but also enhanced the oxidation ability of the photoinduced hole. The doped sulfur substitutes for the lattice nitrogen in triazine rings of PI to form the S-C bond and changes the distribution of negative charge in the two-dimensional plane of PI. The enhanced photocatalytic activity of SPI in the degradation of methyl orange is ascribed to the strong oxidation ability of the photoinduced hole of SPI and an effective suppression to the recombination of electrons and holes.