Anodic TiO₂ Nanotube Arrays: Effect of Electrolyte Properties on Self Ordering of Pore Cells

Abstract

The formation of self-organized, highly ordered TiO₂ nanotube arrays have been widely studied with an aim to enable precise control of nanotube morphologies and properties. Electrochemical anodization process has attracted considerable attention due to its simplicity, low cost, and reliable fabrication technique for the arrayed nanotubular films. This work presents a facile pathway to achieve the uniform anodic TiO₂ nanotube arrays with open pores through systematically manipulating the synthesis parameters and properly incorporating the solvent additives. Using diethylene glycol containing hydrofluoric acid as the electrolyte model, the conductivity-titanium concentration relation has been investigated, and thus the self ordering regimes in terms of construction architecture of nanopores have been established. The porous structure could be obtained only in the critical range of low electrolyte conductivity of approximately <100 μS cm⁻¹, while the electrolyte with higher conductivity was found to yield the well ordered nanotube arrays. Formation of the pore cell structures is strongly dependent upon the combination effect of anodization voltage, electrolyte properties and composition.