Comparison of the Growth of $${\text {TiO}}_{2}$$ Nanotubes in Different Solutions

The kinetics of growth of tubular nanostructures of titanium dioxide (\({\text {TiO}}_{2}\)) obtained by means of the physic-chemical method of electro position under potentiostatic conditions is studied. For this investigation, four tests were carried out where some synthesis parameters were varied in chemical solution: water/fluorhydric acid/ammonium fluoride/ethylene glycol \((\text {H}_{2} \text {O/HF/NH}_{4}\text {F/EG})\) as well as the conditions of anodization. Therefore, the chemical attack in the anodization process is produced by the \(\text {NH}_{4}\text {F}\) and \(\text {HF}\) ions. The morphology of the resulting nanotubes was analyzed through scanning electron microscopy (SEM). The average length of the nanotubes was established, with a maximum value of 980 nm. By means of X-ray diffraction of the samples the structure was analyzed, obtaining a mixed phase of anatase and titanium. Using ultraviolet–visible spectroscopy (UV–Vis), the energy gap of the tests was found at different times of anodization. At 60 min of anodization, the energy gap of the samples varied between 3.56 and 3.68 eV. For a time of 30 min anodization, the energy gap of the samples varied between 3.58 and 3.63 eV with the same parameters of chemical synthesis. With obtaining of the curves of the current as a function of the time of anodization (I vs. t), the different stages of growth of the nanotubes and the regions that these stages define were determined. Analyzing of the behavior the current–time graphs and SEM measurements, it was observed that the best solution of the 4 tests used in this work was that of test 1.