TiO2 Nanowires Grown from Nanoparticles: Structure and Charge Density Study

We report the synthesis of TiO2 nanowires with high aspect ratio using a two step hydrothermal process using TiO2 nanoparticles and 10 M NaOH solvent at a reaction temperature of 180 degrees C. These nanowires are characterized by field emission scanning electron microscope (FE-SEM), transmission electron microscope (TEM), X-ray diffraction (XRD), micro-Raman and X-ray photo emission spectroscopy (XPS). Phase of the nanowires are found to be anatase, confirmed from both XRD and Raman spectroscopic measurements. High resolution electron microscopy (HREM) further supports the anatase structure and selected area electron diffraction (SAED) pattern indicate the single crystalline nature of the nanowires. Addition to these techniques, XPS and EDS refutes the presence of any impurity elements like Na as reported in the literatures. The electronic structures of the nanoparticles and nanowires are studied with maximum entropy method (MEM) using the XRD tools. Nanowires are found to be more ionic than the nanoparticles evidenced from the MEM simulations.