Zn-ZnO core-shell nanotubes: Synthesis, characterization and use as sub-ppm NO2 nanostructured gas sensors

The following paper concerns with the experimental results that the author obtained in recent years in synthesis and characterization of Zinc nanostructures produced via evaporation/condensation methods applied in a flow quartz reactor carrying inert gas. In order to characterize Zn nanostructures SEM, TEM, XRD, DRIFTS diagnostic techniques were used. Here the author refer to the mother paper and report a collection of further results and developments. Dramatically different performances of several Zn nanopowders, different only with respect to the nanostructure size and morphology, which are NPs, NTs and NanoParticle Aggregates (NPAs), were found out at room temperature and RH about 60%. It is demonstrated that the electric response of a NO2 gas sensor built with powder of Zn/ZnO core-shell nanotubes, with external dia 90 nm, is a factor 104 higher with respect to the response of a conventional Zn bulkpowder when the sensor is used to probe sub-ppm NO2 concentration in atmosphere.