Fabrication and EIS Characterization of Titania Nanotube Arrays with Top Non-Tube Layer
TiO2 nanotube arrays were fabricated in the electrolyte containing 0.25wt% NH4F, 2.5vol% water and the ethylene glycol for various hours at room temperature by anodization of Ti foil in this paper. Some anodized specimens were annealed at 450°C for 3 hours. Electrochemical Impedance Spectroscopy (EIS) was employed to measure electrochemical parameters of anodized specimens. The morphology and crystalline structure of anodized products were characterized by Field Emission Scanning Electronic Microscopy (FESEM), X-ray Diffraction (XRD) and Transmission Electronic Microscopy (TEM). A non-tube layer appears on nanotube arrays with the increase in anodization time. Anodized TiO2 nanotube arrays have an amorphous structure, which transfers to anatase structure after annealing at 450°C. A new equivalent circuit R(CR(R(QR)(CR))) was proposed to fit EIS data. The results show that the charge transfer resistance at the electrode/electrolyte interface controls the electrochemical process of TiO2 nanotubes.
Enhou Han, Guanghong Lu and Xiaolin Shu
X. L. Li et al., "Fabrication and EIS Characterization of Titania Nanotube Arrays with Top Non-Tube Layer", Materials Science Forum, Vol. 689, pp. 350-354, 2011