Improving the electrochemical properties of polyaniline by co-doping with titanium ions and protonic acid

Polyaniline co-doped with titanium ions and protonic acid was synthesized in aqueous H2SO4 solution containing Ti(SO4)2 (pH 2), and was characterized via Fourier-transform infrared spectra, UV–vis spectroscopy, X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy and cyclic voltammetry. Its conductivity was 2.8 S cm−1 at room temperature (25 °C), which is the same order of magnitude as polyaniline doped with protonic acid (5 S cm−1). Compared with polyaniline doped with protonic acid, it showed a better redox reversibility and cycling stability in aqueous pH 4.0 media, even in an acetate electrolyte (pH 4.0). It could be a promising material for several applications due the increase of the operating pH window of polyaniline in an aqueous environment.