Structural and spectroelectrochemical (UV-vis and IR) studies of nanocrystalline sol-gel derived TiO2 films

Nanocrystalline TiO2 films with a high surface roughness were prepared by the sol-gel route from titanium (IV) iso-propoxide and brij 56 surfactant. XRD and TEM showed that the films consisted predominantly of anatase nanoparticles embedded in an amorphous phase. Addition of the surfactant significantly increased the intensity of the surface hydroxyl modes between 3600 and 3750cm-1 in IR spectra. Spectroelectrochemical measurements of the films in 0.1M LiOH electrolyte revealed optical modulation beyond 70%T. Slow-scan cyclovoltammetry showed that bleaching occurred in two steps, suggested to correspond to anatase and amorphous phase. The changes that occur during intercalation and deintercalation were followed by ex-situ IR transmission measurements in the regions of Ti-O, carbonate and surface hydroxyl bands.