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Ambient humidity is an important parameter that affects the manufacturing and storage of several industrial and agricultural goods. In the view of the Internet of Things (IoT), single sensors could be associated with an object for smart monitoring enabling optimum conditions to be maintained. Nevertheless, the production of cost-effective humidity sensors for indoor and outdoor environmental monitoring currently represents the main bottleneck in the development of this technology. Herein we report the results obtained with sensors exclusively made of cellulose and polyaniline (cell/PANI) under strictly controlled relative humidity (30–50 RH%) and temperature (21 1 C) achieved with a climatic chamber that simulates the conditions of indoor air humidity, and at different RH% in a lab test chamber set-up. Cell/PANI sensors, prepared with a simple, inexpensive, and easily scalable industrial paper process, show a linear trend with a slope of 1.41 mA RH%−1 and a percentage of sensitivity of 13%. Response time as well as percentage of sensitivity results are similar to those of a commercial digital-output relative humidity and temperature sensor (DHT22) employed in parallel for comparison. The commercial sensor DHT22 has a sensitivity of 14%. This low-cost sensor has potential applications in agriculture, food monitoring, and medical and industrial environments as a disposable sensor for humidity detection.

The research work described in this thesis concerns materials for both energy storage and sensoristics applications. Firstly, the synthesis and characterization of magnetite (Fe3O4) functionalyzed with [3-(2-propynylcarbamate)propyl]triethoxysilane (PPTEOS) capable to reduce the gold precursor chloroauric acid (HAuCl4) without the need of additional reducing or stabilising agents is described. These nanoparticles were tested to improve performances of symmetric capacitors based on polyaniline and graphite foil. Energy storage applications were investigated also during six months stay at EPFL University of Lausanne where an investigation about different tailored catalysts for Oxygen Evolution Reaction in a particular Redox Flow Battery was carried out. For what concerns sensing applications, new materials based on cellulose modified with polyaniline and poly(2-acrylamido-2-methyl-1-propanesulfonic acid) (PAAMPSA) were synthesized, characterized and applied to monitor pressure, humidity, heart rate and lastly, bread fermentation in collaboration with the University of Fribourg and Zurich. The characterizations of all the materials investigated compriseed numerous techniques such as infrared attenuated total reflectance spectroscopy (IR-ATR), thermogravimetric analysis (TGA), scanning and transmission electron microscopy (SEM and TEM), alongside linear and cyclic voltammetry (LSV and CV), electrochemical impedance spectroscopy (EIS) and chronoamperometric analyses.

Magnetic Fe 3 O 4 (magnetite) nanoparticles are synthesized via a chemical precipitation route in different alkaline environments (NH 3 or NaOH) and subsequently functionalized with a (propynylcarbamate)triethoxysilane moiety, with the aim of promoting the nucleation and subsequent stabilization of gold nanoparticles. The propynylcarbamate group is able to capture the gold precursor (HAuCl 4 ), spontaneously reduce it, and stabilize the resulting Au nanoaggregates. The obtained results show that though the dimensions of the starting magnetite substrate depend on the base used in the preparation, they remain unaltered upon the subsequent modification. Conversely, the average Au nanoparticle dimensions can be conveniently tailored as a function of the base used in Fe 3 O 4 preparation and the presence/absence of the organic functionalization. The smallest dimensions (15 nm) are obtained for AuNP supported on propynylcarbamate-functionalized Fe 3 O 4 prepared in the presence of ammonia. Magnetization measurements highlight that all the Au/Fe 3 O 4 nanocomposites display a superparamagnetic behavior and those obtained using ammonia showed consistently smaller Hc and Mr values (av. values of 7.4 Oe and 0.8 emu/g) than those prepared with sodium hydroxide (av. values of 28 Oe and 2.8 emu/g).

Self-supporting membranes built entirely of carbon nanotubes have been prepared by wet methods and characterized by Raman spectroscopy. The membranes are used as supports for the electrodeposition of Pt nanoparticles without the use of additional additives and/or stabilizers. The Pt precursor is an ad hoc synthesized ammonium-ethylimidazolium chloroplatinate(IV) salt, [NH3(CH2)2MIM)][PtCl6]. The Pt complex was characterized using NMR spectroscopy, XRD, ESI-MS, and FTIR spectroscopy. The interaction between the Pt-carbon nanotubes nanocomposites and hydrogen is analyzed using electrochemical and quartz microbalance measurements under near-ambient conditions. The contribution of the Pt phase to the hydrogen adsorption on nanotube is found and explained by a kinetic model that takes into account a spillover event. Such a phenomenon may be exploited conveniently for catalysis and electrocatalysis applications in which the hybrid systems could act as a hydrogen transfer agent in specific hydrogenation reactions. Adsorption advantage: Self-supporting membranes of carbon nanotubes are prepared and used as supports for the electrodeposition of Pt nanoparticles by using an ad hoc synthetized ammonium-ethylimidazolium chloroplatinate(IV) salt as Pt precursor. The hydrogen adsorption on Pt-carbon nanotubes nanocomposites is studied experimentally by electrochemical and quartz microbalance measurements and explained by a kinetic model that takes into account a spillover event.

Indium tin oxide (ITO) substrates were functionalized with fluoroalkylsilanes (FAS) having formula RFC(O)N(R)(CH2)3Si(OMe)3 (1, R = H, RF = C5F11; 2, R = CH3, RF = C5F11; 3, R = H, RF = C3F7) and containing embedded amide moieties between the perfluoroalkyl chain and the syloxanic moiety. Subsequently, Au nanoparticle deposition (AuNP) onto the ITO-FAS functionalized surfaces was carried out by immersion into a solution of citrate-stabilized AuNP. The ITO-FAS and AuNP/ITO-FAS modified systems were characterized by various complementary techniques and compared with AuNP/ITO modified with RF(CH2)2Si(OEt)3 (4, RF = C6F13), free from functional groups between the fluorinated tail and the syloxanic moiety. The results showed that only ITO glasses modified with 1, 2 and 3 displayed an oleophobic, as well as hydrophobic, behaviour and that the AuNP Surface Coverage (SC %) directly depended on the fluoroalkylsilane nature with the following trend: 60% ITO-2 > 16% ITO-3 > 9% ITO-1 > 3% ITO-4. The obtained results revealed that, in organosilane 2, the presence of a methyl group on the amide nitrogen increases the steric hindrance in the rotation around the N CO bond, resulting in the co-presence of two stable conformers in comparable amounts. Their co-presence in solution, combined with the lack of intermolecular N H⋯OC N hydrogen bonds among the anchored molecules, has dramatic influences on the functionalized ITO, yielding a disorderedly packed coating able to accommodate a large quantity of AuNP. These results indicate that AuNP can act as excellent probes to evaluate the coating layer quality but, at the same time, it is possible to tune the gold loading on electroactive surfaces depending on the chemical structure of the used fluorinated silane.

Gold nanoparticles (AuNPs) were anchored on alkynyl carbamate-functionalized support materials having the suitable features for application as catalysts in continuous-flow packed bed reactors. The functionalization step was carried out by grafting with the difunctional organosilane [3-(2-propynylcarbamate)propyl]triethoxysilane (PPTEOS) three commercial micrometer-sized oxide supports, i.e. silica, alumina, and titania. The alkynyl-carbamate moieties were capable of straightforwardly reducing the gold precursor HAuCl4 yielding the supported AuNPs systems Au/SiO2@Yne, Au/Al2O3@Yne, and Au/ TiO2@Yne. A comparison among the three materials revealed that silica allowed the highest organic functionalization (12 wt %) as well as the highest gold loading (3.7 wt %). Moreover, a TEM investigation showed only for Au/SiO2@Yne the presence of homogeneously distributed spherically shaped AuNPs (average diameter 15 nm). Au/ SiO2@Yne is an efficient catalyst, both in batch and flow conditions, in the oxidation of a large variety of alcohols using H2O2 as the oxidizing agent at a temperature of 90 °C. Furthermore, under flow conditions, the catalyst worked for over 50 h without any significant decrease in the catalytic activity. The catalytic activity of the three catalysts was evaluated and compared in the oxidation of 1-phenylethanol as a model substrate. We found that the flow approach plays a strategic role in preserving the physical and chemical integrity of the solid catalysts during its use, with remarkable consequences for the reaction conversion (from 2% in batch to 80% in flow) in the case of Au/TiO2@Yne.

Our research group has previously reported the preparation of different silica supported gold nanoparticles (AuNPs) catalytically active in the reduction of nitrophenol to aminophenol. [1, 2] Recently, the focus of our research has shifted towards continuous flow nanocatalysis and for applications in packed bed reactors we have anchored AuNPs on commercial micrometer oxide supports (SiO2, Al2O3, TiO2), previously modified by grafting of the organosilane [3-(2-propynylcarbamate)propyl]triethoxysilane (PPTEOS). After thorough characterization, the catalytic activity of these systems has been evaluated in the oxidation of a large variety of primary and secondary alcohols, both under batch and continuous flow conditions. [3] We now present the results in the field of the hydroamination of alkynes catalysed by Au/SiO2@Yne and the new, magnetically recoverable Au/Fe3O4@Yne catalyst. [1] S. Fazzini , D. Nanni , B. Ballarin , M. C. Cassani , M. Giorgetti , C. Maccato, A. Trapananti, G. Aquilanti, and S. I. Ahmed, J. Phys. Chem. C. 116 (2012) 25434−25443; M. Giorgetti, G. Aquilanti, B. Ballarin, M. Berrettoni, M. C. Cassani, S. Fazzini, D. Nanni, and D. Tonelli, Anal. Chem. 88 (2016) 6873-6880; [2] S. Fazzini, M. C. Cassani, B. Ballarin, E. Boanini, J. S. Girardon, A.S. Mamede, A. Mignani, and D. Nanni, J. Phys. Chem. C. 118 (2014) 24538-24547; M. C. Cassani, B. Ballarin, D. Barreca, E. Boanini, E. Bonansegna, G. Carraro, S. Fazzini, A. Mignani, D. Nanni, and D. Pinelli, RSC Adv. 6 (2016) 25780-25788. [3] B. Ballarin, D. Barreca, E. Boanini, M. C. Cassani, P. Dambruoso, A. Massi, A. Mignani, D. Nanni, C. Parise, and A. Zaghi, ACS Sus. Chem. Eng. 5 (2017) 4746-4756.

Metal/organosilane/oxide sandwich structures were prepared via a two-step self-assembly method. First, indium tin oxide (ITO) substrates were functionalized with the following fluoroalkylsilanes (FAS): RFC(O)N(H)(CH2)3Si(OMe)3 (1, RF = C5F11), containing an embedded amide between the perfluoroalkyl chain and the syloxanic moiety, and RF(CH2)2Si(OEt)3 (2, RF = C6F13). Subsequently, Au nanoparticles (AuNPs) introduction in the obtained systems was carried out by controlled immersion into a solution of citrate-stabilized AuNPs. The physico-chemical properties of the target materials were thoroughly investigated by using various complementary techniques. Finally, the application of such systems as catalysts for methanol electro-oxidation under alkaline conditions was investigated, revealing the synergistical role played by FAS and AuNPs in promoting a remarkable electrocatalytic activity.