Surface and electrochemical analysis for the understanding of TiO₂ nanopores/nanotubes changes in post‐elaboration treatment

Abstract

The electrochemical stability of TiO 2 nanoarchitecture fabricated in fluoride electrolyte presented in this paper is related to 2D and 3D geometries that present a shift from nanopores toward nanotubes. The fabrication conditions involve a 60 V applied voltage for 2 hours of anodizing in order to create the ordered structures, in a mixture of low-water glycerol electrolyte and fluoride. With the use of different ultrasonication times, a variety of nanotubes/nanopores were observed. The surface interfacial aspects were investigated mainly by surface microscopy and hydrophilic/hydrophobic balance for the grown structures ultrasonicated at various periods of time. The electrochemical behavior of the nanotube-structured surface was performed by potentiodynamic evaluation and electrochemical impedance spectroscopy in a simulated body fluid solution. As a most important result, all surface analysis and electrochemical data interpretation permitted the proposition of a model for elaboration of different nanostructures from nanopores to nanotubes. These different surface nanoarchitectures were obtained as a result of ultrasonication at various periods of time.

Effect of Counter-ion and Solvent on the Morphology and Barrier Layer Properties of Nanoporous/Nanotubular TiO2Films Grown by Anodization in Fluoride Containing Media

“…The values of R a are in the same range of magnitude of those reported by other authors. 16,[43][44][45][46] In the three cases a similar trend was observed with E F , presenting a maximum that depends upon the electrolyte employed, but the film growth in aqueous media containing NH 4 F showed the highest roughness in all cases. It is worth mentioning that anodic films obtained in ethylene glycol showed lower values of R a , with a lower dispersion as is shown by the error bars in Figure 2; this behavior indicates a lower chemical attack occurred in these films.…”

Long-term corrosion behavior and biocompatibility testing of titanium-based alloy covered with nano-crystalline hydroxyapatite

“…Nyquist impedance spectra (Fig. ) of the coated Ti–20Nb–10Zr–5Ta alloy depicted large semicircles indicative of capacitive, passive, protective behavior ; the in time enlarging of their diameters shows the enhancement of the protective capacity of the HA nano‐coating, its growth, thickening that promote the bone development .…”

Surface characterisation and electrochemical stability of anodised new alloy in simulated physiological electrolytes

“…4) revealed large arcs, capacitive loops with bigger diameters for anodised alloy that implies higher resistances compared with those of the bare alloy. The impedance values are higher for the anodised alloy proving that the anodised film increased the insulating, protective properties of the alloy native passive film [17,26,[38][39][40][41][42][43].…”

“…The cathodic potentiostatic polarisation may assure a very good adhesion of the oxide nanolayer with the substrate and a favourable microstructure for cell development; using different solution compositions, the obtained oxide coating can include various ions or molecules from the biofluid that enhance the cell activity. The potentiostatic anodisation was performed in acid or neutral solutions and good results were observed; the acid solutions consisted of sulphuric acid , phosphoric acid with different additions specially fluoride ions , hydrochloric acid , electrolytes based on fluoride ions , phosphate buffer solutions , nickel sulphate solutions or physiological solutions . Controlling the polarisation parameters, electrolyte composition and concentration, scan rates, pH, temperature and time oxides with improved properties for effective implantation may be obtained.…”