Copper oxide nanowires for surface ionization based gas sensor

This work focuses on the development of surface ionization gas sensors based on copper oxide (CuO). CuO nanowires were prepared by thermal oxidation starting from a thin film of metallic copper deposited by RF magnetron sputtering. In addition to the well-known conductimetric sensors, we have developed another kind of device depending upon a different sensing mechanism, namely surface ionization (SI). SI phenomenon involves ions formed by the adsorption of gas molecules on heated solid surface, the electron transfer from the adsorbed species to the electrode surface and the extraction of the ion adsorbates into free space by an external electrical field. Our preliminary results show that humidity plays an important role in the ions formation and so in sensors performance. For this reason we have done a systematic study on the interaction mechanism of target molecules with hydroxyl groups adsorbates on CuO surface, explaining the experimental results in terms of acidity/basicity.