In situ synthesis and enhanced visible light photocatalytic activities of novel PANI-g-C3N4 composite photocatalysts

Novel polyaniline-graphitic carbon nitride (PANI-g-C3N4) composite photocatalysts with different PANI:g-C3N4 ratios were synthesized by "in situ" deposition oxidative polymerization of aniline monomer in the presence of g-C3N4 powder cooled in an ice bath. The resulting PANI-g-C3N4 composite photocatalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), ultraviolet-visible diffuse reflection spectroscopy (DRS), X-ray photoelectron spectroscopy (XPS) and photoluminescence spectroscopy (PL). The photoelectrochemical measurements were performed using several on-off cycles of visible light irradiation. The photocatalytic activities of the novel photocatalysts were evaluated using methylene blue as a target pollutant. The PANI-g-C3N4 composites exhibit obviously enhanced photocatalytic performance under visible light irradiation, which is much higher than that of TiO2 (P25). The synergistic effect between PANI and g-C3N4 is found to lead to an improved photo-generated carrier separation. A possible photocatalytic mechanism of PANI on the enhancement of visible light performance is proposed to guide further improvement of their photocatalytic activity.