Synthesis of monodispersed SnO₂ nanocrystals and their remarkably high sensitivity to volatile organic compounds

In situ detection of volatile organic compounds (VOCs) in the atmosphere has become particularly important because of their detrimental effects on human health and the environment. To develop high-performance gas sensors capable of detecting VOCs in ppb concentrations, we prepared SnO₂ nanocrystals by a liquid-phase synthesis method. Nearly monodispersed SnO₂ nanocrystals (ca. 3.5 nm) were prepared by heating tin(IV) acetylacetonate in dibenzyl ether in the presence of oleic acid and oleylamine at 280 °C. The prepared nanocrystals exhibited high thermal stability against crystal growth, even at 600 °C, allowing for the fabrication of nanoparticulate gas-sensing films. The sensor device using the nanocrystals calcined at 600 °C exhibited significantly high sensor responses to VOCs such as ethanol, formaldehyde, and toluene at low ppm concentrations.