International audienc

Abstract:In the present work, core TiO 2 and ZnO oxide nanofibers were prepared by electrospinning, then shell oxide (ZnO, TiO 2 ) layers were deposited on them by atomic layer deposition (ALD). The aim of preparing ZnO and TiO 2 nanofibers, as well as ZnO/TiO 2 and 3 TiO 2 /ZnO nanocomposites is to study the interaction between the oxide materials when a pure oxide fiber is covered with thin film of the other oxide, and explore the influence of exchanging the core and shell materials on their photocatalytic and gas sensing properties.The composition, structure and morphology of the pure and composite nanofibers were studied by SEM-EDX, TEM, XRD, FTIR, UV-Vis and Raman. The photocatalytic activity of the as-prepared materials was analyzed by UV-Vis spectroscopy through decomposing aqueous methyl orange under UV irradiation. The gas sensing of the nanofibers was investigated by detecting 100 ppm NH 3 at 150 and 220 °C using interdigital electrode based sensors.

Abstract. Applying atomic layer deposition (ALD) very thin zinc oxide (ZnO) films were deposited on quartz resonators, and their gas sensing properties were studied using the quartz crystal microbalance (QCM) method. The gas sensing of the ZnO films to NO 2 was tested in the concentration interval between 10 and 5000 ppm. On the basis of registered frequency change of the QCM, for each concentration the sorbed mass was calculated. Further characterization of the films was carried out by various techniques, i.e. by SEM-EDS, XRD, ellipsometry, and FTIR spectroscopy. Although being very thin, the films were gas sensitive to NO2 already at room temperature and could register very well as low concentrations as 100 ppm, while the sorption was fully reversible. Our results for very thin ALD ZnO films show that the described fast, simple 3 and cost-effective technology could be implemented for producing gas sensors working at room temperature and being capable to register in real time low concentrations of NO 2 .