Structural and optical properties of ex-situ polymerized PAni-TiO2 nanocomposite

Abstract

Abstract The nanocomposite of anatase TiO2 and polyaniline (PAni) was synthesized by ex situ polymerization. TiO2 was mixed with polyaniline at two different molar quantities viz. 0.2 M and 0.3 M. TiO2 powder were prepared by the hydrothermal sol-gel method and PAni was synthesized by an oxidative polymerization method. The samples were characterized by UV-Vis spectrophotometer; Fourier transforms infrared (FTIR) spectrometer, X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM) and photoluminescence (PL). UV-Vis absorption spectra have been acquired in the range from 300 nm to 800 nm. Composition with TiO2 causes a slight red shift of the peak at 310 nm in absorption spectra due to the interactions between conjugated polymer chains and TiO2 nanoparticles arising from π-π* transition. The band gap of the composites has been calculated from absorption spectra. Morphological information of the prepared composites has been obtained from FESEM. Images of the PAni-TiO2 nanocomposite show uniform spherical type morphological features. XRD patterns reveal that as the molar concentration of TiO2 increases the amorphous nature of the composites disappears and the presence of anatase phase due to TiO2 becomes prominent. The vibrational bands present in the nanocomposite have been identified from FTIR spectra. PL spectra were recorded in the range of 300 nm - 700 nm. The spectra show two prominent peaks at 399 nm and 470 nm. Small peaks are also observed between 450 nm - 500 nm assigned to free electron recombination from conduction band to the recombination center at the ground state.