Electrically conductive polyaniline sensitized defective-TiO2 for improved visible light photocatalytic and photoelectrochemical performance: a synergistic effect

Abstract

Sulfonated polyaniline@pure-TiO₂ (s-Pani@p-TiO₂) and polyaniline@defective-TiO₂ (s-Pani@m-TiO₂) nanocomposites were prepared by the in situ oxidative polymerization of aniline in the presence of TiO₂ (p-TiO₂ and m-TiO₂) nanoparticles followed by sulfonation with fuming sulfuric acid. Defect-induced TiO₂ (m-TiO₂) nanoparticles were obtained by an electron beam (EB) treatment of commercial TiO₂ (p-TiO₂) nanoparticles. The resulting s-Pani@p-TiO₂ and s-Pani@m-TiO₂ nanocomposites were characterized by UV-visible diffuse absorbance spectroscopy, photoluminescence spectroscopy, transmission electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. Polyaniline (Pani) was dispersed uniformly over the defective m-TiO₂ surface with intimate contact on the interface to act cooperatively with the deliberately induced defects to achieve remarkably enhanced properties. The s-Pani@m-TiO₂ nanocomposite showed better photocatalytic activity and photoelectrochemical performance than s-Pani@p-TiO₂ under visible light irradiation, which was attributed partly to the sensitizing effect of Pani, the narrowed band gap of m-TiO₂ and the effective interfacial interaction between Pani and m-TiO₂. The electrical conductivity measured using a four-point probe revealed s-Pani@m-TiO₂ to have much higher conductivity than s-Pani@p-TiO₂. Therefore, s-Pani@m-TiO₂ may be used for a wide range of applications owing to its higher charge mobility and high photocatalytic activity. The proposed methodology can also be a potential route for the development of nanocomposites via EB treatment and can be commercialized.