ZnO nanocrystals by chemical route for optical gas sensing
Authors: Baratto C., Todros S., Faglia G., Sberveglieri G., Epifani M., Siciliano P.
Autors Affiliation: Dept of Chemistry and Physics, C.N.R.-INFM, University of Brescia, Brescia, Italy; Istituto per la Microelettronica e i Microsistemi, C. N. R.-I. M. M., Lecce, Italy
Abstract: ZnO nanocrystals were prepared from the decomposition of zinc(II) 2-ethylhexanoate. Soluble nanocrystals with a size ranging from about 5 to 8 nm were obtained. The powders obtained were tested as optical gas sensor based on photoluminescence (PL) variation with NO2, ethanol and relative humidity at room temperature (RT). The surface capping of the ZnO nanocrystals was modified by substituting the native dodecylamine capping with phosphorus or sulfur containing ligands, in order to investigate the effect of the surface chemistry onto the sensing properties. The reversible PL variations that we observed at RT are opposite to that reported in literature for ZnO, probably due to surface properties of the powders examined. We demonstrated that PL is increased by interaction with NO2 at few ppm concentration and decreased upon interaction with reducing gases like ethanol. Further investigation on luminescence mechanisms and its variation due to NO2 are underway to determine the PL variation mechanism.
KeyWords: Chemical routes; Dodecyl amines; Luminescence mechanisms; Optical gas sensing; Optical gas sensors; Reducing gas; Relative humidities; Room temperature; Sensing property; Surface capping; Variation mechanisms; ZnO; ZnO nanocrystal, Atmospheric humidity; Ethanol; Gas detectors; Humidity control; Nanocrystals; Phosphorus; Powders; Semiconducting zinc compounds; Sensors; Sulfur; Surface chemistry; Surface properties; Zinc; Zinc oxide, Nanocrystalline powdersDOI: 10.1109/ICSENS.2008.4716681