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Few layer graphene/SiO2/SiC (G/SiO2/SiC) core-layers-sheath nano-heterojunctions were obtained by a new easy and cheap designed procedure by thermal annealing at atmospheric pressure and low temperature on 3C-SiC powder derived from exhausted activated carbon. Recycled SiC was chosen as growth substrate to realize a convenient process and to increase the added value of the recycled, combining the favourable properties of different substances. SiC powder and the advanced materials obtained were carefully characterized by the combining use of different techniques: transmission electron microscopy (TEM) with EDAX probe, scanning electron microscopy (SEM), X-ray diffraction analysis, Raman spectroscopy, thermogravimetric analysis coupled with quadrupole mass detector (TG-DTG-MASS). © Copyright 2017, AIDIC Servizi S.r.l.

Few layer graphene/SiO2/SiC (G/SiO2/SiC) core-layers-sheath nano-heterojunctions were obtained by a new easy and cheap designed procedure by thermal annealing at atmospheric pressure and low temperature on 3C-SiC powder derived from exhausted activated carbon. Recycled SiC was chosen as growth substrate to realize a convenient process and to increase the added value of the recycled, combining the favourable properties of different substances. SiC powder and the advanced materials obtained were carefully characterized by the combining use of different techniques: transmission electron microscopy (TEM) with EDAX probe, scanning electron microscopy (SEM), X-ray diffraction analysis, Raman spectroscopy, thermogravimetric analysis coupled with quadrupole mass detector (TG-DTG-MASS).

The results of the quantitative Raman analysis, performed on multi-walled carbon nanotubes produced by iron-catalysed chemical vapour deposition, are utilised for deriving a scaling law for the growth parameters. A semi-empirical approach, already successfully applied to different materials and growth techniques, is utilised and demonstration is given that the reaction outcome, in terms of yield to C deposits and crystalline perfection of nanotubes attained, analytically depends on the growth parameters through a single dimensionless combination of them.

The crucial role of precursor gas (PG) and of catalyst support (CS) in the growth of multi-walled C nanotubes (MWCNTs) by iron-catalysed chemical vapour deposition (CVD) is evidenced. This is accomplished by comparing structural and morphological properties of MWCNTs synthesised by the use of different PGs (ethane and isobutane) and CSs (silica and alumina). The results of analyses, carried out on catalysts and C deposits by scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), Raman spectroscopy (RS), thermo-gravimetry (TG) and X-ray diffraction (XRD), demonstrate that Al2O3-supported catalysts are more efficient than SiO2-supported ones in decomposing hydrocarbons. The use of i-C4H10 as PG allows reducing Fe-encapsulation and improving yield (YC) and selectivity, so as the largescale production (YCN900 wt.%) of high-quality nanotubes can be operated even at moderate reaction temperature (600 °C) after proper calibration of Fe-load (29 wt.%) and catalyst reduction temperature (500 °C).

The CO and NO2 sensing properties of iron oxide thin films doped with Au and Zn and prepared by a liquid-phase deposition method (LPD) have been investigated. The undoped Fe2O3 sensor was found to be sensitive to NO2 but not to CO. The addition of Zn increases the sensitivity at low temperature towards NO2 and decreases strongly the intrinsic resistance of the iron oxide film. The addition of gold was necessary to obtain a detectable response to CO, the Au-doped ZnO sensor was found the most sensitive to CO. By operating at an appropriate temperature, these sensors could be able to detect selectively CO and NO2, with negligible humidity cross-sensitivity.

On Pt-Ge catalysts cinnamaldehyde is hydrogenated to cinnamyl alcohol with a selectivity of 90-95% at conversions higher than 90%.

The rate of propene hydrogenation has been measured, in a flow system, over platinum supported on inorganic materials (Al,O, and MgO) and polyamides (Nylon 66 and Nylon 610). The effect of adding tin to Pt/Nylon 66 has also been investigated. The orders of reaction with respect to the reactants have been found to be strongly influenced by the nature of the support used. In particular, higher values of the reaction order with respect to propene have been found on Pt/Nylon samples. The presence of electron-deficient sites is suggested. Addition of Sn causes a drastic decrease in catalytic activity, suggesting Sn enrichment on the surface and/or an electronic interaction between the two metal components.

Silicon carbide nanopowders (SiC_PL) were prepared via thermal plasma synthesis. The electrocatalytic activity of the SiC_PL coated glassy carbon electrode (GCE) towards the electrochemical oxidation of dopamine (DA), ascorbic acid (AA), and uric acid (UA), was characterized by cyclic voltammetry (CV), in 0.1 M phosphate buffer solution (PBS) at pH 7. The peaks of oxidation for DA, AA, and UA result well separated on the modified electrode in contrast with the behavior shown on bare GCE. A low limit of detection (LOD) of 0.043 μM was found at the SiC_PL coated GCE. In a real sample, the recovery rates of the added compound were 98.8%, 106.5% and 100.7%, indicating a potential for the SiC_PL electrode to determine DA in real conditions. The results of the characterization as supercapacitor electrode show that the specific capacitance for SiC_PL is of 151.2 F/g at 0.12 A/g. After 2.5 × 105 cycles SiC electrode still retains about 90% of its initial capacitance showing good stability.

A novel study about the synthesis of zirconia and calcia-stabilized zirconia powders were carried out by DC thermal plasma starting from cheap precursors as the carbonates. Different operational parameters were investigated to explore the effects of the process conditions, such as the plasma torch power and the gas flow rate on the composition and the morphology of the powders. The products phase changes from a metastable tetragonal to monoclinic/tetragonal mixture. Basically a main tetragonal phase was obtained at low torch power (7 kW) while the amount of monoclinic phase linearly rises with the power, up to 66 wt% at 26 kW of plasma power and high gas flow rate. The gas flow rate also affects the shape and the size of the powder, where high values reduce powder aggregation and enhance the spherical shape. The best results were achieved at 22 kW of plasma power and high gas flow rate, with powders of roundness about 79% and a wide particle size distribution. Adding the calcium carbonate to the zirconium carbonate (corresponding to 8 wt% CaO in the final mixture), the plasma treatment mainly produces a tetragonal phase zirconia, that at 1400 °C in furnace changes in a stable cubic phase. These powders could be made suitable for further industrial applications after proper treatments.

Submicronic powder of silicon carbide was synthesized in a pilot novel radiofrequency plasma torch reactor. The precursors were pyrolysis char and silica powders both with micrometric size. The mass rate of the precursor powder varied in the range 600-2500 g/h. The maximum test time was approximately 3 h. With the goal to increase the process yield, several technical measures were implemented. Silicon carbide yield was above 70 wt% when the plasma flame was confined by a tube that prolonged the residence time of the reactants at the useful temperature for the advancement of reaction. The silicon carbide was characterized by XRD, SEM, and DLS. Both α and β-crystalline phases were detected. Resumo Pó submicrométrico de carboneto de silício foi sintetizado em um novo reator piloto de tocha a plasma por radiofrequência. Os precursores foram pós de cinza de pirólise e sílica com tamanhos micrométricos. A taxa de massa do pó de precursor variou na faixa de 600-2500 g/h. O tempo máximo do teste foi de aproximadamente 3 h. Com o objetivo de aumentar o rendimento do processo, várias medidas técnicas foram implementadas. O rendimento de carbeto de silício foi superior a 70% quando a chama de plasma foi confinada por um tubo que prolongou o tempo de residência dos reagentes à temperatura útil para o avanço da reação. O carbeto de silício foi caracterizado por DRX, MEV e DLS. Ambas as fases cristalinas α e β foram detectadas.

Carbon nanotubes-grafted-carbon fibers have been tested to improve composite performances; in particular in aerospace this substrate was tested as conductive light material in substitution of metallic foils. In this work, hierarchical growth of carbon nanotubes (CNTs) has been achieved on recovered carbon fiber (rCF). The process has been performed by thermal catalytic chemical vapour deposition (CCVD) starting from liquid precursor (such as ethanol); different combinations of process parameters were tested and the growth was verified by Scanning Electron Microscopy (SEM) and Raman Spectroscopy. The electrical characterization of the samples shows an increase of conductivity in presence of CNTs. © 2018 Author(s).

Dendrimer-functionalized multi-walled carbon nanotubes (MWCNT) for heavy metal ion removal from wastewaters were developed. Triazole dendrimers (TD) were built directly onto the carbon nanotube surface by successive click chemistry reactions affording the zero- and first-generation dendrimer-functionalized MWCNT (MWCNT-TD1 and MWCNT-TD2). The Moedritzer-Irani reaction carried out on the amino groups present on the MWCNT-TD2 sample gave the corresponding α-aminophosphonate nanosystem MWCNT-TD2P. Both MWCNT-TD2 and MWCNT-TD2P nanosystems have been characterized by physical, chemical, and morphological analyses. Their chelating abilities towards the toxic metal ions Pb2+, Hg2+, and Ni2+ and the harmless Ca2+ ion have been experimentally evaluated in the two different sets of experiments and at the salt concentrations of 1 mg/mL or 1 μg/mL by inductively coupled plasma mass spectrometry (ICP-MS). The results of these studies pointed out the interesting chelating behavior for the phosphonated nanosystem towards the Hg2+ ion. The complexation mode of the best chelating system MWCNT-TD2P with mercury was investigated through density functional theory (DFT) calculations, suggesting a chelation mechanism involving the two oxygen atoms of the phosphate group. The synthesized dendrimers, supported on the multi-walled carbon nanotubes, have shown the potential to be used for the selective toxic metal ion removal and recovery.

We demonstrated the suitability of polymer composites filled with silicon carbide (SiC) powders derived from a recycling process for applications in electronic devices manufacturing. SiC powders have been synthesized from the process byproducts and used as fillers in the formulation of polystyrene (PS)/SiC composites, which have been used in the preparation of substrates using the solution-casting technique. Different substrates have been prepared by changing the concentration of SiC in the composite in the range from 6.7 to 67 wt % and used in simple electronic devices by performing gold contacts in both planar and stacked configurations. The electrical behaviors of both stacked and planar devices were investigated in direct current (DC) and alternate current (AC) regimes. The experimental results showed that charge percolation could be considered an explanation for the abrupt change in the differential conductivity observed around 30 wt %. Fowler-Nordheim tunneling at high fields has been found to be compatible with static characteristics and with high-frequency AC measurements and, therefore, charge tunneling between SiC islands has been proposed as the physical mechanism provoking the changes in charge transport in the substrates investigated. From this first experimental analysis, it appears that SiC/PS composites could suit their use in tunneling-gate dielectrics (i.e., in transistors suitable for their applications in nonvolatile random-access memory) for low concentrations or as a continuous semiconducting media when SiC is dispersed in high-concentration composites. © 2016 American Chemical Society.

Graphene has been obtained at atmospheric pressure and low temperature on exhausted activated carbon-derived SiC nanoparticles. The graphenes growth, traced by online analyzers, has been obtained from an external source of carbon, in particular by methane/hydrogen chemical vapor deposition (CVD). Recycled SiC has been chosen as growth substrate to carry out a convenient process and to increase the added value of the recycled, combining the favorable properties of different substances. Therefore, the SiC powder and the composite material obtained have been carefully characterized by the combined use of different techniques and tested as supercapacitor electrodes. The results show a very high capacitances up to 114.7 F/g for SiC alone and three times higher in the presence of graphene with an excellent cycle stability. © 2016 American Chemical Society.

Plasma synthesized SiC powder obtained from quartz and carbonaceous residue of waste tires was successfully sintered at 1925 ℃ by pressureless liquid-phase method using yttria and alumina as sintering aids (T-SiC). Comparison with sintered SiC obtained from commercial powder (C-SiC) put in evidence of similar sintered density (98%T.D.), but much finer microstructure of T-SiC than that of C-SiC. T-SiC also showed higher flexural strength than C-SiC both at room temperature (508 vs. 458 MPa) and at 1500 ℃ (280 vs. 171 MPa). Difference in liquid phase was responsible for the differences in hardness and fracture toughness. The high value of the Young’s modulus of T-SiC (427 MPa) confirmed the high degree of sinterability of this powder and that it can be a promising candidate for structural applications with high added value. © 2016, The Author(s).

Throughout the last century the increasing human activities in Antarctic region, particularly research expeditions, fishing, and tourism amplified the risk of oils spills at these high latitudes of the meridional hemisphere. A number of studies have been focused on chronic hydrocarbon contamination near Antarctic research stations revealing the presence and persistence of these human-derived contaminants. Marine ship-source oil spills in Antarctic region can have significant impacts on the marine environment. The key factors to effectively fight oil spills are a careful selection and proper use of the equipment and materials best suited to the critical local conditions. Despite the significant advances in the field of environmental recovery after an “oil spill” episode, research has recently shown that the usual techniques are often less effective than expected. This issue become much more relevant in the Antarctic case, not only for the incomparable environmental value of the Antarctic region but also for the extreme environmental conditions and the great distances from properly equipped centers, that make unfeasible sending naval vessels. Scope of the STRANgE Project is the preliminary design of a prototype floating platform, parachutable by plane, able to intervene as quickly as possible for the containment, removal and treatment/storage of the oil slick. New sorbent nanostructured materials and specialized Antarctic bacteria applications constitute the main innovations of this Project.

Silicon carbide powders have been synthesized from tires utilizing a patented recycling process. Dynamic light scattering, Raman spectroscopy, SEM microscopy, and X-ray diffraction have been carried out to gather knowledge about powders and the final composite structure. The obtained powder has been proven to induce resistive switching in a PMMA polymer-based composite device. Memory effect has been detected in two-terminal devices having coplanar contacts and quantified by read-write-erase measurements in terms of level separation and persistence.

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