Nanocomposites based on titanium dioxide and polythiophene: Structure and properties

A composite of polythiophene (PTh) and nanoscopic titanium dioxide (TiO2), possessing core-shell structure, was prepared via oxidative polymerization of thiophene by iron (III) chloride in the presence of TiO2 particles. The morphology of the obtained composite particles was studied by transmission electron microscopy (TEM), proving the core-shell structure of the prepared nanocomposite. The chemical structure of the composites was investigated by Raman spectroscopy. The electrophoretic deposition (EPD) technique was used as a method to prepare composite layers on various conducting substrates (platinum and ITO plate). The characteristics of the composite layer after EPD were studied by electrochemical methods. The photoelectrical properties of PTh and TiO2 in the nanocomposites were studied as well. In the photoelectrochemical spectra (depending on the applied potential), the characteristic anodic peak of TiO2 at λ = 340 nm and cathodic peak of PTh around λ = 530 nm were observed. A bandgap energy, Eg = 1.95 eV and a direct electron transition of PTh were found. A cathodic peak in the photocurrent spectra was detected unexpectably also around 340 nm, and ascribed to the photoelectrical activity of the TiO2 core. The redox processes in PTh were investigated via cyclic voltammetry (CV) and electrochemical impedance microscopy (EIS).