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

Abstract

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.