This paper studies the effect of H2O and NH4F content on morphology and barrier layer properties of TiO2nanotubes grown by potentiostatic anodization in ethylene glycol-based electrolytes. The increase in these two variables leads to an increase in the chemical attack of the formed oxide. However, each of these variables plays a different role in the formation of TiO2nanotubes. On the one hand, a higher percentage of H2O in the electrolyte leads to a transition from a nanoporous to a nanotubular structure, as well as to a greater diameter of the tubes and a decrease in their length and barrier layer thickness. In contrast, a higher NH4F concentration decreases nanotube diameter and increases their length modifying barrier layer properties due to insertion of F-ions into the lattice. This diminishes the barrier layer resistance, but increases both the adsorption and the diffusion coefficient of F-ions. The different roles of H2O and NH4F in film formation are also associated with the presence of sub-oxides detected by XPS. © 2013 Springer-Verlag Berlin Heidelberg.
Acevedo-Peña, P., Lartundo-Rojas, L., & González, I. (2013). Effect of water and fluoride content on morphology and barrier layer properties of TiO<inf>2</inf>nanotubes grown in ethylene glycol-based electrolytes. Journal of Solid State Electrochemistry, 2939-2947. https://doi.org/10.1007/s10008-013-2212-2