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.