Utilizing sulfuration of supercritical fluid treatment to improve sensitivity and humidity resistance of chip-type gas sensors.

This research investigates a novel supercritical-fluid sulfuration (SCF-S) treatment used to enhance the sensitivity of SnO 2 -based chip-typed gas sensors and enable them to resist the influence of moisture during the alcohol detection. The fluid of supercritical state possesses helpful features, such as high permeability of gas and high solubility of water. The SCF-S process introduces the sulfuration penetrating the whole tin oxide membrane with sulfur bonding and thin film transformation. The surface morphology and the lattice structure have been confirmed by Scanning Electron Microscope (SEM) and X-ray diffraction analysis (XRD), respectively. To further verify the composition content after the novel SCF-S treatment, the qualitative and quantitative analyses are conducted, and both show the sulfur doping results. Moreover, different electronic properties are gained in the experiments where the concentration of alcohol and environment humidity vary. In order to understand the sensing reaction model after SCF treatment, response performance at different temperatures and the reliability of the reaction model are further investigated. From the present results, it is demonstrated that SCF-S process has a good potential in terms of the sensitive and selective detection of alcohol. ● The sulfuration treatment helps to enhance sensitivity of SnO 2 -based gas sensors. ● Sensors treated with sulfuration treatment can operate with low working temperature. ● The treated SnO 2 sensor has high selectivity to alcohol molecule and moisture. ● The treated gas sensor is completely unaffected with humidity. ● Related reaction model is also built to illustrate the SCF sulfuration improvement. [ABSTRACT FROM AUTHOR]