Synthesis and characterization of cobalt antimonate nanostructures and their study as potential CO and CO 2 sensor at low temperatures

Cobalt antimonate (CoSb2O6) nanostructures were prepared using the microwave-assisted colloidal method, employing cobalt nitrate, antimony chloride, ethylenediamine and ethyl alcohol. The solvent was evaporated through microwave radiation at 140 W. The precursor material was dried at 200 °C and then calcined at 300, 400, 500, and 600 °C in static air. The crystalline phase of the material was found at 600 °C by means of X-ray diffraction. Morphology was analyzed through scanning electron microscopy, finding octahedral particles with an edge length between 3 and 50 µm, and other particles of nanometric size. The size of these irregularly shaped nanoparticles was estimated of ~ 17.6 nm by means of transmission electron microscopy. UV–vis analyses of semiconducting powders revealed a forbidden band of ~ 1.82 eV. For the gas detection experiments, thick films and pellets were made of CoSb2O6 powders (600 °C). The tests were carried out in air, CO, and CO2 atmospheres at different gas concentrations and operating temperatures. The cobalt antimonate nanoparticles showed high sensitivity at 300 °C and 300 ppm of CO, and a good dynamic response at 100 ppm of CO2.