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Gold nanoparticles (Au-NPs) are electrochemically synthesized in the presence of tetra-alkyl-ammonium stabilizers and used as active element in Field Effect capacitive gas sensors. Before use, the sensing area is treated by a relatively mild annealing procedure aimed to partially remove the organic stabilizer without loosing the nano-structured character of the particles. Both pristine and annealed materials have been subjected to a spectroscopic and morphological characterization (by means of UV-Vis, XPS, TEM, SEM techniques). Preliminary results on the application of AuNPs as gate material for NOx sensing are reported. The sensor is able to detect NOx with appreciable selectivity and low response towards the other tested gases (C3H6, CO, H2, NH3).

Field-Effect Transistors comprising layers of lipids have been developed and characterized from the electrical point of view. Lipid layers-OTFT are proposed as novel devices for perspective application in the detection of analytes from aqueous samples.

A two-step bottom up preparation protocol is proposed as a useful tool for the controlled modification of tin oxide films by means of Pd nanoparticles (PdNPs). Colloidal palladium is prepared via an electrolytic process that affords for a core-shell particle structure, while nanostructured tin oxide films are prepared following a sol-gel process. Pd/SnOx composite layers are obtained adding a proper aliquot of pre-formed PdNPs to the tin oxide precursor solution. The nanomaterials surface chemical composition is addressed by X-ray Photoelectron Spectroscopy. Preliminary results on the application of Pd/SnOx as active layers in chemiresistor-type gas-sensing devices are reported, as well.

Catalysts made of Pd supported on ZrO2 were prepared via a sacrificial anode electrosynthesis route. Tetragonal zirconia was added to an electrolytic cell assembled for the preparation of colloidal Pd nanoparticles. Several samples were prepared varying the electrolysis time and thus the Pd loading in the nanocomposite. XRD analysis showed the presence of the tetragonal ZrO2 mainly and some small reflections due to monoclinic ZrO2. BET surface areas were in the range 70–80 m2 g-1. The morphology and surface chemical composition of the nano-materials were, respectively, assessed by transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) analyses. From TEM evidence, the Pd-ZrO2 powders revealed to be composed of spherical Pd nanoparticles (average core diameter: 6.9 ± 1.8 nm) evenly dispersed on the surface of ZrO2 nano-grains (average grain size: 150 ± 70 nm, average size of crystallites composing each grain: 40 ± 10 nm). XPS allowed to quantify the surface elemental composition of the nanomaterials and to study the different chemical states of the nano-dispersed palladium. Catalysts were tested for CH4 total combustion and for CO oxidation. The conversion increased with Pd content in the CH4 combustion experiments whereas decreased with Pd content in the CO oxidation experiments. The apparent activation energies were about 25 and 9 kcal mol-1 for CH4 combustion and CO oxidation, respectively. Hypothesis was made that different reaction mechanisms and different active sites were probably involved in the two reactions.

Palladium-fluoropolymer nanostructured composites (Pd-CFx) are deposited by a separate and simultaneous sputtering of bulk Teflon and palladium targets in a vacuum chamber. Such nano-material can find application as active layer in sensing devices, as it swells when exposed to the vapors of organic solvents such as acetone, chloroform, 2-propanol. Ellipsometry shows that the swelling extent linearly depends on the solvent partial pressure in the measuring chamber. Moreover, Pd-CFx sensitivity and selectivity features are different to those of a parent gold-fluoropolymer (Au-CFx) nanocomposite, investigated in previous studies. In particular, Pd-CFx layers are generally more sensitive than Au-CFx ones, particularly in the case of chlorinated solvents, which are scarcely detectable by Au-CFx nanocomposites. The material morphological and chemical structure has been investigated by means of atomic force and transmission electron microscopies along with X-ray photoelectron (XPS) and Fourier transform infra-red spectroscopies. The analytical characterization demonstrates that morphological similarities exist between Pd-CFx films and Au-CFx ones having the same metal volume fraction f. XPS also reveals an almost identical surface structure for the dispersing polymer matrix of homologous Pd-CFx and Au-CFx films. Metal fluorides and oxides are identified as well and differences in the materials sensing performances are then ascribed to the presence of different amounts of these species that also have a different chemical reactivity and selectivity.

Eukaryotes, such as fungi, can be harmful pathogen agents, and the control of their bioactivity is critical as humans are eukaryote organisms, too. Here, copper/polymer nanocomposites are proposed as antifungal spinnable coatings with controlled copper-releasing properties. The tests of the bioactivity show that fungal growth is inhibited on the nanocomposite-coated plates, and the antifungal activity can be modulated by controlling the Cu nanoparticle loading.