The directed preparation of TiO2 nanotubes film on FTO substrate via hydrothermal method for gas sensing application

In this research, we directly synthesized TiO2 nanotubes film on Fluorine doped Tin oxide (FTO) substrate via hydrothermal method from commercial TiO2 in NaOH solution at 135 degrees C for 24 hours. The samples were characterized by X-ray diffraction (XRD) pattern, field emission scanning electron microscopy (FESEM) and transmitting electron microscopy (TEM). The average diameter of TiO2 nanotubes (TNTs) is about 10-12 nm and their length is about a few hundred nanometers. The sensitivity ability of TNTs increases as the gas concentration increases and developing to the highest sensitivity of TNTs is 2.4 at 700 ppm of the ethanol concentration. The same as the gas concentration, the sensitivity of TNTs increases when the temperature increases. Besides, the sensitivity of samples at 250 degrees C is doubled compared to samples determined at 100 degrees C.