Development of nanomaterials and nanocomposites for sensor applications

In the everyday life, nanotechnology is gaining more and more space, covering many fields of applications, developing new nanomaterials. Due to their particular optical, electronic and catalytic properties, they are pushing the development of increasingly smaller, better and faster products. This PhD work aims to explore the applicability of these nanomaterials, specifically in the sensors field. The whole work can be divided into two main parts. The first one is based on the use of gold nanoparticles (AuNPs), suitably functionalized with bifunctional dithiols, to be applied in the sensing detection of vapour mercury. Gold nanoparticles, exploiting their high surface area to volume ratio and their strong affinity with mercury, present great potential in the sensing application. They show advantages in sensitivity, selectivity, stability and at last a very cheap cost, in order to be employed in wide areas of monitoring. In fact, gold promptly adsorb mercury on its surface for a defined time of exposition, to be subsequently thermally desorbed and quantified with an analytical instrument. A second step of this work regarded the behaviour of two diffusive shelters, to be used with this AuNPs adsorption material. A comparative study has been performed both in at outdoor and indoor environments. The second part of this work is based on the investigation of conducting polymers, such as polyaniline (PAni). This polymer, and the so obtained composite material, acquire interesting properties which can be used in optoelectronics, electrochemistry, catalysis or, as in the present work, used as sensor devices, detecting some dangerous gases, harmful to the human health (NH3, H2S, NO). Starting from its pristine undoped form, with a subsequent appropriate doping process, it has been added to some functionalized metal nanoparticles (AgNPs-TR), leading in this way to the formation of a composite compound. These polymers have been subsequently deposited on suitable interdigitated supports (by casting or dipping deposition) and subsequently exposed at low concentrations of pollutants (few ppb). From the measurements, very low detection limits, combined with a good sensitivity and fast recovery time, have been reached in some gases detection.