Hydrothermal growth of photoelectrochemically active titanium dioxide cauliflower-like nanostructures

Abstract

Hierarchical titanium dioxide nanostructures have been synthesized by a simple and cost-effective hydrothermal deposition method onto the conducting glass substrates. In order to study the effect of titanium tetrachloride precursor quantity on the growth of TiO2; the thin films of TiO2 have been synthesized with the variations in the TiCl4 from 0.4mL to 1.0mL at the interval of 0.2mL. These films are characterized for their optical, structural, compositional, morphological properties using UV-vis spectrophotometer, Photoluminescence, X-ray Diffraction, High resolution transmission electron microscopy, X-ray Photoelectron Spectroscopy and Field Emission Scanning Electron Microscopy techniques. The optical band gap energy is found to increase from 2.74 to 3.06eV with the increase in TiCl4 quantities exhibiting a blue shift. XRD patterns show the formation of polycrystalline TiO2 with the tetragonal crystal structure possessing rutile phase. Rise in the TiCl4 quantity leads to the decrease in the particle size. The chemical composition and valence states of the constituent elements were analysed by XPS. FESEM images showed the formation of cauliflower-like structure at the highest TiCl4 precursor quantity. The films were photoelectrochemically active with the maximum current density of 202μA/cm2 for the sample prepared at 1.0mL.