Physical and electrochemical characterization of nanostructured composites formed by TiO2 templates and PEDOT–PPS films

We report the physical and electrochemical characterization of nanostructured composites formed by TiO2 templates and PEDOT–PPS films. TiO2 templates were prepared by sol–gel techniques using TiCl4 and TiF4 as the titania precursors, and also by adding a soluble polymer at the initial stages of the TiCl4 sol–gel synthesis to induce porous oxide networks. The effect of different precursors and annealing environments in the crystallite and particle size of the templates was followed by XRD and SEM studies, and correlated to the electrochemical properties of TiO2 templates dip-coated in a conducting polymer solution (PEDOT–PSS 1.3%). We found that the microstructure had a strong influence in the adsorption of the conductive polymer, which shows superior electrochemical activity in matrices with abundant surface hydroxylation, broad particle size distribution and residual carbon. Cyclic voltammetry and electrochemical impedance data revealed the differences between the several TiO2/PEDOT–PSS systems, with the best performance observed in systems based on TiO2 templates obtained from the TiCl4 sol–gel route and containing residual mesoporous carbon.