Enhanced gas sensing properties of SnO2: The role of the oxygen defects induced by quenching

Oxygen defects have been considered to play an important role on the gas sensing properties of the sensor. In this work, oxygen vacancies are produced by quenching the commercial SnO2 and characterized by the X-ray photoelectron spectroscopy (XPS), adsorption and impedance spectra. Impedance spectra indicate that the quenched samples have a significant increase in conductivities, as well as a large reduction in activation energy from 1.14(1) to 0.20(1) eV, with the quenching temperature increasing. Furthermore, the gas sensors based on quenched SnO2 are prepared and gas sensing experiments give strong evidence that the oxygen vacancies enhance the sensor performances. By increasing the concentration of oxygen vacancies, the sensor displays a higher response toward ethanol (100 ppm) at 300 °C.