Angela Bertuna

Tungsten oxide nanowires for chemical detection

Tungsten oxide nanowires have been synthesized on alumina substrates in order to fabricate sensing devices. Metallic tungsten films have been deposited by RF magnetron sputtering and then oxidized in a controlled atmosphere, in order to obtain a dense mat of nanowires. Two batches of samples have been prepared, starting from 18 nm and 180 nm tungsten films, and the influence of the sputtering temperature on the morphology has been investigated. Raman and XRD spectroscopies were used to confirm the crystalline structure of the material. The chemical sensing performance of n-type tungsten oxide nanowires has been evaluated towards some oxidizing and reducing species, together with the influence of relative humidity. Fabricated WO3 nanowires exhibit a very good sensitivity, especially for the detection of NH3, NO2 and CO.

Metal oxide nanostructures: preparation, characterization and functional applications as chemical sensors

Preparation and characterization of different metal oxide (NiO, WO3, ZnO, SnO2 and Nb2O5) nanostructures for chemical sensing are presented. p-Type (NiO) and n-type (WO3, SnO2, ZnO and Nb2O5) metal oxide nanostructures were grown on alumina substrates using evaporation–condensation, thermal oxidation and hydrothermal techniques. Surface morphologies and crystal structures were investigated through scanning electron microscopy and Raman spectroscopy. Furthermore, different batches of sensors have been prepared, and their sensing performances towards carbon monoxide and nitrogen dioxide have been explored. Moreover, metal oxide nanowires have been integrated into an electronic nose and successfully applied to discriminate between drinking and contaminated water.

Metal Oxide Nanowire Preparation and Their Integration into Chemical Sensing Devices at the SENSOR Lab in Brescia

Metal oxide 1D nanowires are probably the most promising structures to develop cheap stable and selective chemical sensors. The purpose of this contribution is to review almost two-decades of research activity at the Sensor Lab Brescia on their preparation during by vapor solid (n-type In2O3, ZnO), vapor liquid solid (n-type SnO2 and p-type NiO) and thermal evaporation and oxidation (n-type ZnO, WO3 and p-type CuO) methods. For each material we’ve assessed the chemical sensing performance in relation to the preparation conditions and established a rank in the detection of environmental and industrial pollutants: SnO2 nanowires were effective in DMMP detection, ZnO nanowires in NO2, acetone and ethanol detection, WO3 for ammonia and CuO for ozone.