Authors: S. di Stasio, V. Dal Santo
Affilation: National Research Council of Italy (CNR), Italy
Pages: 1019 - 1022
Keywords: chemical sensors, nanostructures, physi-sorption, chemi-sorption, gas molecule physics
Zinc nanostructures synthesized with different morphologies from the same evaporation/condensation technique are studied with concern to surface reactivity to NO2 by Diffuse Reflectance Infrared Fourier Transformed Spectroscopy (DRIFTS). Synthesis of nanopowders is obtained, according to previous work, by gas flow thermal evaporation at 540 °C of bulk Zn grains. Two types of Zn powders are obtained and studied in experiments. The first one is collected on the cold walls of the reactor as a deposit produced by thermophoretic effect. It is constituted by grains ( 10 m) originated by the stratification of smaller aggregates ( 200 nm) and isolated primary particles ( 50 nm) born in the gas flow. The second type of powder is grown from the condensation of Zn chemical vapors and it is constituted mainly by hollow Zn nanofibers with external and internal diameter about 100 and 60 nm. Preliminary characterization of the two types of powders is made by SEM, TEM, XRD. Thereafter, the two types of samples are studied by DRIFTS at variable temperature. Comparison is made between the home-synthesized nanopowders with respect to commercial Zn standard dust. The Zn hollow nanofibers when exposed to NO2 are found to exhibit dramatic reactivity, which is not observed at all either in the case of clustered aggregate zinc or of commercial Zn dust powders.