Facile Formation of Self-Organized TiO2 Nanotubes in Electrolyte Containing Ionic Liquid-Ethylammonium Nitrate and Their Remarkable Photocatalytic Properties

Abstract

The oriented TiO2 nanotube arrays (NTs) are identified as a stable, active, and recyclable photocatalytic surface. However, their photoactivity is strictly dependent on morphology (especially length), which could be controlled by anodic oxidation parameters, including electrolyte properties. To control the morphology a series of NTs were successfully synthesized by a novel approach where ionic liquid (IL), ethylammonium nitrate [EAN][NO3], was used as an addition to an organic electrolyte. Using scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, diffuse reflectance UV–vis spectroscopy, and photoluminescence spectroscopy, we are able to show how electrolyte composition influences nanotubes’ surface properties and photocatalytic activity. It was found that the change in the amount of [EAN][NO3] in the electrolyte used for anodization in the range from 0.05 to 1.0 wt % affected dynamic viscosity, conductivity, and surface tension of the electrolyte and finally altered the morp...