Hierarchical nanocomposites of polyaniline nanorods arrays on graphitic carbon nitride sheets with synergistic effect for photocatalysis

Abstract

Hierarchical nanocomposites of polyaniline (PANI) nanorod arrays on graphitic carbon nitride (g-C3N4) sheets (CN-PANI) were successfully synthesized by dilute polymerization under −20°C. The photocatalytic activities of the CN-PANI composites were evaluated using methylene blue (MB) and methyl orange (MO) as model pollutants. The CN-PANI composites displayed much higher photocatalytic activity than the pure g-C3N4 and PANI under visible light irradiation. Meanwhile, the degradation efficiency of MO was higher than that of MB under same irradiation conditions, which was mainly attributed to the difference of adsorption processes. The different adsorption behaviors of MB and MO on composites were due to the fact that they carry different charge, i.e., MO and CN-PANI composites have the opposite charge, leading to the enhanced MO adsorption due to the strong electrostatic forces between them. Conversely, MB had the same charge with PANI, thus resulting in a low adsorption capacity due to the electrostatic repulsion. By careful investigation of the influence parameters, a possible mechanism was proposed, i.e., the synergistic effect of g-C3N4 and PANI was responsible for the effective photogenerated charge separation, the large specific surface area and the energy band structure.