Hydrothermal synthesis of TiO2 nanorods as sensing membrane for extended-gate field-effect transistor (EGFET) pH sensing applications

Titanium dioxide nanorods were prepared by hydrothermal method using titanium tetrachloride TiCl4 as a precursor solution and an expanded gate field effect transistor's (EGFET) sensing membrane has been used for pH sensing applications. The TiO2 nanorods were grown onto fluorine-doped tin oxide FTO coated glass substrates at a hydrothermal reaction temperature of 170 degrees C for 6 h. The effect of precursor solution TiCl4 and hydrochloric acid HCl concentrations on the crystal form of TiO2 nanorods was analyzed. The morphology, crystal structures, chemical composition, and the size distribution of the TiO2 nanorods were characterized by X-ray diffraction (XRD), external field scanning electron microscopy (FESEM) with energy dispersive spectroscopy (EDS), and transmission electron microscopy (TEM) images. Under strongly acidic conditions, the structural and morphological studies showed that the rutile TiO2 nanorods shape is the predominant phase. The TiO2 nanorods sensor exhibited high sensitivity of 78.25 mV/pH and large linearity of 99.27% with good repeatability of 0.23% in a wide sensing range of pH 2-12 with good stability, reliability and showed lower hysteresis value of 9.1 mV. The TiO2 nanorod pH sensor's high measured sensitivity makes it a feasible contender for a wide range of applications, including pH sensors and biosensors. (C) 2021 Elsevier B.V. All rights reserved.