UV-blue spectral down-shifting of titanium dioxide nano-structures doped with nitrogen on the glass substrate to study its anti-bacterial properties on the E. Coli bacteria

In this study, titanium dioxide (TiO2) nano-structures including nanoparticles and nano-wires are synthesized on the glass substrate at temperatures of 300, 400 and 500 °C using thermal chemical vapor deposition technique. Doping with nitrogen are done in three different temperatures including 300, 400, 500 °C to obtain optimum nitrogen doping content. To investigate the optical properties, crystalline structure, morphology, thickness and chemical components of the nano-structures, UV-Visible spectrometer, X-Ray diffraction, field emission scanning electron microscopy and energy dispersive X-ray spectroscopy are used, respectively. Results show that the temperature and location of substrate play a significant impact on the morphology and structure of as-grown TiO2 nano-structures. The crystal structure of the obtained layers including TiO2 nano-structures on the glass are consisted anatase and rutile crystalline phases. The atomic percentage of nitrogen in TiO2 nano-structures at a doping temperature of 400 °C increase in comparison to the other two doping temperatures. In addition, observing the peak of TiN and Ti3.72 O8.00 N2.24 structures in the X-Ray pattern at doping temperature of 400 °C, refer to dope TiO2 nano-structures with a significant amount of nitrogen. Moreover, the reduction of band gap at about 0.4 eV, for N-TiO2 nano-structures grown at 400 °C, confirms the enhancement of photo-catalytic activity in the visible region. Antibacterial properties of pure titanium dioxide and doped with nitrogen were examined under dark, sunlight and UV light for E. Coli bacteria. The results show that growth of E. Coli bacteria significantly reduces in solution using N-TiO2/glass system treated at 400 °C in NH3/N2 ambient under sunlight due to down shifting of TiO2 band gap in compared with other samples.