Construction of a ternary g-C3N4/TiO2@polyaniline nanocomposite for the enhanced photocatalytic activity under solar light.

The combination of two or more semiconductor materials for the synthesis of new hybrid photocatalyst could be a good approach to enhance the visible light absorption, electron-hole (e-/h+) pair separation rate and photocatalytic decomposition of the organic contaminants. Herein, a facile in situ oxidative polymerization method has been used for the synthesis of visible light active g-C3N4/TiO2@polyaniline (g-C3N4/TiO2@PANI) nanocomposite for the decomposition of the congo red (CR) under the solar light irradiation. Prior to making the composite of TiO2 (P25) with g-C3N4 and polyaniline, a lamellar structure was generated onto the TiO2 brim by alkali hydrothermal treatment to enhance the surface area and adsorption properties. The PL and UV-visible analysis clearly showed the fast separation of the e-/h+ pair, and reduction in the bandgap energy of the g-C3N4/TiO2@PANI nanocomposite. The results revealed TiO2, PANI and g-C3N4 showed the synergestic behavior in the g-C3N4/TiO2@PANI nanocomposite and greatly enhanced the photocatalytic degradation of the CR. The photocatalytic decomposition of the CR was almost 100% for 20 mg/L at pH 5, 7 and 180 min. The reusability study of the spent catalyst showed the 90% degradation of CR after four consecutive cycles indicate that g-C3N4/TiO2@PANI nanocomposite is a stable and efficient catalyst. The high efficiency and reusability of the g-C3N4/TiO2@PANI nanocomposite could be attributed to the higher visible light absorption and sensitizing effect of the g-C3N4 and PANI.