Self-assembled zirconia nanotube arrays: fabrication mechanism, energy consideration and optical activity

Abstract

We present a comprehensive roadmap for the precise control of the dimensions and optical properties of anodically fabricated zirconia nanotubes. The effects of anodization time, applied voltage, solvent composition, as well as fluoride and water content are investigated. The length of the resulting nanotubes showed a strong dependence on the concentration and mobility of F⁻ ions, whilst O²⁻ ion content was found to play a key role in controlling the nanotube wall thickness. A new insight into the formation of Zirconia nanotubes is introduced and discussed based on the Point Defect Model (PDM). Also, the energy consumption in the fabrication process of the nanostructured electrodes is modelled based on the involved thermodynamics and kinetic aspects. The effect of the dimensions of the nanotubes on the optical characteristics of the arrays was studied using Finite Difference Time Domain (FDTD). The results show a decrease in transmittance with increasing length and wall thickness, and decreasing pore size of the nanotubes. The reported results provide deep insight into the structure–property relationships of ZrO₂ nanotubes, which will be of great help in large-scale industrial applications.