Development of pure rutile TiO2 and Magneli titanium sub-oxide microstructures over titanium oxide-seeded glass substrates using surfactant-free hydrothermal process

Titanium oxide seed layer was coated over glass substrates by sol-gel spin coating method. Single-step surfactant-free hydrothermal process developed titanium oxide microstructures over the titanium oxide-seeded glass substrates. Various morphologies of titanium oxide microstructures, varying from coral reefs to flower-like morphology were evolved by changing HCl concentration (1 and 3 M) in the precursor solution and growth temperature (GT) (120, 150 and 180C) of the hydrothermal process. Structural studies confirmed the formation of rutile TiO2, TiO2+Ti2O3 and Ti4O7 microstructures due to varying the concentration of HCl (1 and 3 M) in the solution and GTs. Morphological studies revealed the possibility of engineering coral reefs, cauliflower, flowers, ball, cactus and jasmine flower-shaped microstructures of titanium oxide films by tuning the growth parameters. The indirect band gap of the titanium oxide microstructures derived from UV-Vis absorption spectra lies in the range of 2.9-3.02 eV.