Investigation of the Gas-Sensing Performance of Electrospun TiO2 Nanofiber-Based Sensors for Ethanol Sensing

This paper presents an investigation on the sensitivity toward ethanol of a gas sensor based on TiO2 nanofibers deposited by electrospinning between interdigitated Pt electrodes. Morphological/structural characterizations by SEM/TEM show the formation of fibers, having a length up to hundreds of p.m and a diameter of about 60 nm, constituted of TiO2 nanograins in the brookite phase. The sensitivity was evaluated by measuring, under constant polarization, the electrical current of the oxide nanofibers network at different ethanol concentrations (50, 100, and 150 ppm) and different operating temperatures (350 degrees C, 400 degrees C, and 450 degrees C). The experimental results show that the response increases linearly with increasing both the ethanol concentrations and the operating temperature. In particular, the hest performance of the device toward the ethanol sensing is obtained when it works at 450 degrees C. An equivalent circuit, modeling the electrical behavior in relation with the material microstructure, was proposed by carrying out ac impedance spectroscopy investigation during gas sensing tests.