Interfacial properties of self-organized TiO2 nanotubes studied by impedance spectroscopy

The semiconductor properties of the interface TiO2/electrolyte in high organized porous oxide structures were analyzed by means of impedance spectroscopy near the flat band potential. The impedance and capacitance studies performed on the as-anodized and thermally treated samples (anatase) indicate the presence of a duplex structure formed by (1) the oxide at the bottom of the pores and (2) the walls of pores with different donor densities and surface state concentrations.