A high sensitivity gas sensor for formaldehyde based on CdO and In2O3 doped nanocrystalline SnO2

The gas-sensing characteristics of In2O3 and CdO doped nanocrystalline SnO2 compounds for formaldehyde were investigated in this study. The phases of the resulting materials and the morphologies of the sensing layers were characterized by x-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. Indirect-heating sensors using SnO2-In2O3-CdO compounds as sensitive materials were fabricated on an alumina tube with Au electrodes and platinum wires. All measurements were performed at several operating temperatures from 100 to 180 degrees C. Good gas-sensing responses to formaldehyde have been found for all the prepared samples. It is shown that the sensors exhibited high sensitivity at low operating temperature (133 degrees C), making them promising candidates for practical detectors for formaldehyde.