Tuning the optoelectronic and surface properties of TiO2 nanotubes

Abstract

Nanostructured TiO2 is a widely researched material because of its semiconducting property, biocompatibility, nontoxic nature, and therefore, applications are plenty in the fields of energy, catalysis, sensing, and medicines. Tailoring the properties of this material remains a challenge without contaminating and compromising various aspects. In this work, we demonstrate the tailoring of a few important properties such as bandgap, electrical conductivity, and wettability of anatase TiO2 nanotubes using low-energy argon ion irradiation. The ion beam modification of structure, morphology, and surface chemistry are probed using scanning electron microscopy, X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, UV–visible spectroscopy, and photoluminescence spectroscopy. The observed ion beam modifications such as morphological deformation, surface defects, and joining are successfully predicted by TRI3DYN simulation. While the electrical conductivity is increased significantly, the surface starts repelling water after ion irradiation. The bandgap reduces noticeably after ion irradiation. First principles-based simulation reveals that both O and Ti vacancy play important roles in controlling conductivity, bandgap reduction, and change of contact angles. Such tunability can have a strong impact on various applications involving TiO2 nanotubes.