Towards enhanced performances in gas sensing: SnO2 based nanocrystalline oxides application

A non-aqueous sol–gel process was implemented for the preparation of SnO2- and In2O3-nanostructured powders. A detailed transmission electron microscopy (TEM), high resolution TEM (HRTEM) and X-ray diffraction (XRD) characterization carried out on the prepared nanomaterials showed that they were composed of single crystallites only slightly aggregated with an average size of 2.2 nm for SnO2 and 20 nm for In2O3. A mixed oxide of composition Sn0.95In0.05Ox was also prepared showing a crystallite size of 2.2 nm.The nanoparticles were directly used for thick film sensor deposition by drop coating and tested as gas sensors in the monitoring of trace level of both oxidizing and reducing gases. In particular, the In2O3-based sensor showed enhanced gas sensing properties toward the oxidizing gas NO2, while for the mixed metal oxide Sn0.95In0.05Ox very interesting gas sensing properties were found towards the reducing gases CO and CH4.