Title: The effect of experimental process on properties of pure TiO2 nanostructure for fast NO2 gas sensor

Abstract

In this study, we reported the impact of spray time and substrate temperature on several properties of TiO2 thin layers elaborated by facile and robust Spray Pyrolysis (SP) technique. The TiO2 thin layers were characterized by the following techniques: X-ray diffraction (XRD), Raman Spectroscopy (RS), Scanning electron microscopy (SEM) and UV-visible spectrophotometer (UV-Vis). The XRD results demonstrated the pure Anatase phase of TiO2 thin layers with the preferential direction along <101> direction. The vibration characteristics of TiO2 have been confirmed by Raman vibratory modes located at 143, 396, 518 and 637 cm-1 which certified the formation of a single phase of TiO2 Anatase. The SEM images showed the formation of granular TiO2 layers. The UV-Vis spectrophotometer displayed the semiconducting properties of TiO2 semiconductor, the band gap energy was ranged between 3.10 and 3.30 eV. All parameters investigated in this study confirmed that TiO2 deposited by the inexpensive spray pyrolysis during 25 min at 500°C had the required properties for gas sensing applications and are in good agreement with those reported in the literature. The sensing properties of the elaborated TiO2 thin films to NO2 showed their high suitability to detect this pollutant gas.