January 29, 2018

Metal Oxide Nanowires: Technologies for Chemical Sensors Preparation

Monday, 29 January 2018 at 11:00 in INF 328

Elisabetta Comini, Sensor Laboratory, University of Brescia, Brescia, Italy



Metal oxides are a class of material widely studied due to their peculiar features and properties. In particular, most of them exhibit a reversible interaction between their surfaces with the surrounding atmosphere. This interaction may lead to a change of some different properties of the material, such as electrical conductance, capacitance, work function or optical characteristics. All metal oxides are in principle sensitive to gases if they are prepared in a sufficiently porous form (high surface to volume ratio and electrical properties controlled by surface states), but in order to be active material in chemical sensors they need to fulfill specific requirements such as sensitivity, selectivity, stability, response speed.
After the introduction of the first method proposed for the preparation of metal oxide in forms of nanobelts [1], research activities were devoted to experiment different techniques that may lead to the formation of quasi one-dimensional structures. At the beginning, the research was focusing on the vapour phase methods that were producing, with cheap instrumentation, high quality nanostructures in terms of crystallinity and stoichiometry.

At SENSOR Laboratory we have thoroughly studied the synthesis of a wide range of metal oxide nanostructures. SnO2, CuO, ZnO, NiO, WO3, MoO3, TiO2, Nb2O5 were successfully synthetized using different techniques: vapour phase evaporation and condensation from powder in controlled environment [2-4], thermal oxidation of a metal film [5,6], electrochemical anodization [7], hydrothermal synthesis [8]. Recently, branched heterostructures have been grown, combining the properties of two different metal oxides (for example NiO-ZnO) to enhance the performances of the devices [9].
Thanks to the peculiar response spectra of each nanostructured material, these devices are ideal candidates to be included into sensors arrays, which could be exploited in many different applications such as environmental monitoring, safety & security, food industry, and many more.

[1] Z. W. Pan, Z. R. Dai, and Z. L. Wang, Science 291, 1947 (2001).
[2] Bianchi, S. et al Sensors and Actuators B, 118 (2006) 204-207
[3] Comini E. et al. Applied Physics A, 88, 45-48 (2007)
[4] N. Kaur et. al., Nanotechnology 27 (20), 205701 (2016)
[5] D. Zappa et al, Sensors and actuators B, 10.1016/j.snb.2013.02.076 (2013)
[6] D. Zappa et al., Anal. Methods, (2015), 7, 2203–2209
[7] V. Galstyan et. Al., Sensors and Actuators: B. Chemical, 209, pp. 1091-1096. (2015)
[8] A. Bertuna et. Al., Procedia Engineering Volume 168, Pages 313-316, (2016)
[9] Kaur, N. et al., Procedia Engineering Volume 168, Pages 1140-1143, (2016)


About the speaker:

Elisabetta Comini received her degree in physics at the University of Pisa in 1996. She received her Ph.D. degree in material science at the University of Brescia. She was appointed assistant professor of physics of matter at Brescia University in 2001, she became full professor in 20016. She has organized several symposiums in the sensing field for Materials Research Society MRS and E-MRS. She was chair of the MRS fall meeting in 2013. She has a high productivity confirmed by the numerous publications on international journals (more than 330) and the high number of invited presentations at conferences. She has received several awards, including the Eurosensors Fellow Award in 2012.

Prof. Comini is a researcher specialised in the growth of metal oxides, particularly nanowires, thin films and the measurement of their electronic, functional and structural properties. She is currently the director of the SENSOR Laboratory at Brescia University.