Effect of Fluoride Concentration and Water Content on Morphology of Titania Nanotubes in Ethylene Glycol Solution

Abstract

Titanium dioxide (TiO2) nanotube arrays were prepared at room temperature by electrochemical anodization of a pure titanium foil in electrolyte solutions containing ethylene glycol as a solvent and de-ionized water and ammonium fluoride as additives. Since the morphology and size of TiO2 nanotubes play critical roles in determining their performance, the control of geometrical parameters of the nanotube arrays including length and inner diameter are of great importance. The present research demonstrates the significant effects of fluoride concentration and water content in anodizing electrolyte on formation of nanotubes and their dimensions. Scanning electron microscope investigation shows that nanotube arrays are no longer formed in very low or very high concentration of ammonium fluoride. Also, increase in fluoride concentration causes increase in lengths and inner diameters of the nanotubes. Moreover, it is evident that the maximum nanotube growth rate was achieved in medium amount of water. In addition, it is found that the nanotube inner diameter increases by adding more water to the solution.

Synthesis of Anodized TiO2 Nanotube Arrays as Ion Sieve for Lithium Extraction

“…However, there is no sign of this layer at higher concentrations (Figure 4(d),(f)). The enlargement of nanotube length from 0.2 to 0.5 % wt is in accordance with the observation by M. Naghizadeh et al, [37] Viscous electrolytes like EG create two different environments along the tube, one inert at the top and other chemically reactive, induced field-assisted dissolution of fluoride ions at the bottom. Thus, the inhibition of the oxide dissolution at the top side of the nanotube allows more deepening of the pores and longer nanotubes.…”

Ordered TiO2 Nanotubes with Improved Photoactivity through Self-organizing Anodization with the Addition of an Ionic Liquid: Effects of the Preparation Conditions

“…%). As reported by Golobstanfard et al, with higher water contents (>3 vol. %), a decrease in the tube length from 2.8 to 2.2 μm with an ethylene glycol-based electrolyte was observed.…”

Photocatalytic and mechanical properties of immobilized nanotubular TiO2 photocatalysts obtained by anodic oxidation: a novel combined analysis

“…Thus, the chemical dissolution of the TiO 2 compact oxide (Eqs. (S7) and (S8)) is reduced, resulting in a thin nanoporous layer on the top of the nanotubular structure [52]. This mechanism is consistent with the evolution of the current density shown in Fig.…”