Titanium-di-oxide (TiO2) concentration-dependent optical and morphological properties of PAni-TiO2 nanocomposite

PAni-TiO2 nanocomposite was prepared by ex-situ oxidative chemical polymerization method. Hydrothermally prepared TiO2 nanoparticles were mixed with PAni (polyaniline) where two different percentage amount of TiO2, viz. 20% and 40% were used during the polymerization reaction. Broad peak around 240 nm in UV-Vis absorption spectra implies the absorbance of TiO2 in nanocomposite in UV region. XRD, TEM, SAED and HRTEM analysis confirms crystalline nature of PAni and PAni-TiO2 nanocomposite. In the composite, TiO2 remains like an amorphous material. FESEM analysis shows a strong effect of TiO2 on the morphology of PAni. PAni exhibits agglomerated nanoparticles while nanoflake, nanorod and nanowire like morphology are observed after composite formation with TiO2. XPS analysis confirms the presence of expected elements in the materials. Photoluminescence emission spectra of the PAni-TiO2, acquired in the range of 300 nm-700 nm, show that the emission intensity is quenched with increasing TiO2 amount in the composite. The broad peak around 400 nm is attributed to the radiative annihilation of excitons. A peak appearing between 450 nm and 500 nm of the composites is assigned to the bandgap recombination of electron-hole pairs. The photocatalytic dye degradation rate of the composite is increased with increase in TiO2 content. For highest content of TiO2 in PAni matrix, photocatalytic dye degradation rate is increased nearly by 100% with respect to pristine PAni.