Studying the formation of nanoporous and nanotubular titanium layers by electrochemical impedance spectroscopy

Nanoporous and nanotubular titanium layers have been obtained via electrolytic etching in a mixed organic-inorganic electrolyte. The formation of layers has been studied in situ by electrochemical impedance spectroscopy. It has been shown that the impedance of an electrochemical cell is governed by the impedance of the contact between the electrolyte and titanium at the bottom of nanoporous and nanotubular layers almost throughout the entire process except the initial period. It has been revealed that the electrical resistance of the space charge region in a titanium layer is higher than the charge transfer resistance at the electrolyte/TiO x interface. This indicates that the rate of the growth of porous and nanotubular layers obtained via etching in an organic-inorganic electrolyte is limited by the transfer of titanium and oxygen ions through an oxide layer instead of the diffusion of ions in the electrolyte.