Browsing by Author "Tavolaro, Adalgisa"

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Graphene synthesis by top-down and bottom-up strategies
(2016-02-26) Cid Perez, Denia marlenis; Pantano, Pietro; Caputi, Lorenzo S.; Tavolaro, Adalgisa
Graphene is a two-dimensional structure arranged in a hexagonal form (similar to a honeycomb) that has unique physicochemical properties and has generated interest in the scientific community for its properties and applications. To produce graphene, several methods are used, all of them can be divided in two approaches: the bottom-up approach and top-down approaches. In this work, both routes will be explored. In the bottom-up approach, the properties of graphene over a mono crystalline nickel surface obtained by chemical vapor deposition (CVD) will be studied. In the top-down approach, natural graphite will be used to construct graphene based materials with innovative approaches. Obtained products are characterized by Auger electron spectroscopy, Low energy electron diffraction, Scanning (SEM)and transmission (TEM) electron microscopy, Raman spectroscopy , X-ray photoelectron spectroscopy (XPS) and Energy electron loss spectroscopy (EELS). As a result, in the bottom-up approach, Cesium restored the linearity of the graphene and it behaved as a free-standing graphene, when is well known that exist a strong interaction between graphene and the metal substrate. In the top-down approach, graphene oxide free-defect layers that are very large and transparent were obtained. Preparated layers chemically seem to coordinate zeolite crystals probably to obtain the necessary energetic stabilization.
L'uso di biomateriali innovativi per la veicolazione di farmaci antitumorali
(2014-12-01) Tavolaro, Palmira; Sisci, Diego; Andò, Sebastiano; Panno, Maria Luisa; Tavolaro, Adalgisa
Llow dimensional materials synthesis, characterization and applications
(2017-02-24) Coello Fiallos, Diana Carolina; Pantano, Pietro; Caputi, Lorenzo; Tavolaro, Adalgisa
This thesis was carried out at the laboratory of the Surface Nanoscience in the Department of Physics of University of Calabria, and at the Institute of Membrane Technology (ITM) of CNR, dealing the study of nanostructured systems with low dimensionality. The first part of the work consisted in the synthesis and characterization of graphite oxide (GO), obtained by chemical oxidation and sonication of natural graphite. We used an innovative oxidation process with respect to those present in the literature, and the resulting material was studied by means of UV-visible and Infrared absorption spectroscopy, Raman and XPS spectroscopies, and by TEM and SEM microscopies. The sonicated graphite oxide (sGO) was tested for adsorption of dyes, with the aim to contribute to research in the field of the reduction of pollutants in the liquid phase. We used Methylene Blue, Acridine Orange and Cresyl Violet dyes, whose kinetics of adsorption on sGO was been meticulously studied by the UV-visible absorption spectroscopy. The results showed that the graphite oxide effectively absorbs the three dyes, and the chemical nature of the adsorption process was evidenced by means the kinetic simulations adopting different models. The second part of the work relates to the synthesis of carbon-based nanostructures of the type "nano-onions" (CNOs), similar to multi-layer fullerenes, of great scientific and technological interest. The CNOs can be obtained by means of arc discharge between carbon electrodes immersed in deionized water. This method was used in this thesis work, and the produced carbonaceous nanomaterials have been characterized by Raman spectroscopy and TEM microscopy. Particular attention has been paid to those nanomaterials that contain a high percentage of CNO, since the arc discharge method also generates carbon nanotubes (CNT) and amorphous carbon. The main finding of the research was the identification of a solid agglomerate on the cathode, consisting almost exclusively of polyhedral CNOs and turbostratic graphite. The genesis of such CNOs is not attributable to a crystallization process of the carbon ions expelled from the plasma zone towards the surrounding water. The evidence of the fact that during the discharge the cathode remains at a temperature certainly lower respect to the anode, has permitted to hypothesize the CNOs training process, in which the carbon ions crystallize in the presence of a temperature gradient in the immediate vicinity of the cathode surface. In the last part of this research activity, I investigated a crystal of Indium Selenium (InSe) by means of different electron spectroscopies, in ultra-high vacuum conditions. Through electron energy loss spectroscopy (EELS) the electronic properties of InSe and its reactivity towards oxygen and air have been studied. The results have allowed to identify the most relevant transitions between electronic states in good agreement with existing theoretical calculations of the electronic structure and density of states. Experimental observations have also shown that the material is very stable with respect to possible oxidizing agents.
Physical and Chemical treatments to produce graphene and their related applications
(2016-02-26) Tubon Usca, Gabriela Viviana; Pantano, Pietro; Tavolaro, Adalgisa; Caputi, Lorenzo
In this work Few Layers Graphene (FLG) and Graphene Oxide (GO) were produced by using physical and chemical treatments, and two types of applications were tested with GO. The first application concerns the Drug delivery in the field of nano-medical treatments, while the second regards environmental remediation for removal of pollutants from water. Few Layers Graphene (FLG) was produced from natural graphite by two methods: i) Sonication in a mixture of solvents, and ii) With the aid of an external agent (zeolite crystals) in the exfoliation process. In the first stage, the mixture was made with two types of solvents: N-methyl-2 pyrrolidone and Dimethylsulfoxide in different ratios. The exfoliation was carried out in that mixtures, then the centrifugation was applied in order to remove unexfoliated graphite. The supernatant suspensions were characterized using Ultraviolet - visible spectroscopy (UV-vis), and Raman Spectroscopy. The Uv-visible analysis and the Raman spectroscopy showed of existence of Few layers Graphene (FLG). In the second stage, the zeolite 4A (Z4A) was selected. The experiments were carried out to improve the exfoliation of graphite, after the exfoliation and centrifugation; the stability was achieved in those that were added the zeolite 4A. Supernatant solutions were characterized by Field Emission Scanning Electron Microscopy (FESEM), Transmission Electron Microscopy (TEM), Electron Diffration, and Raman Spectroscopy. The 3_BS suspension and the 7_F suspension showed the best results; these reached the greatest amount of days in suspension. The Electrical Characterization (EC) was carried out using 3_BS and 7_F suspensions. The drop-casting technique was used over Al2O3 substrates with gold (Au) InterDigitated Electrodes (IDE). The Current–Voltage (I-V) characterization was performed, and the results were averaged for each sample and computed; in order to obtain the 2D resistivity (ρ2D). Finally, an annealing treatment was applied on the Al2O3/Au substrates; afterwards, the resistivity improves, for 3_BS ink by a factor of 1.75 and for the 7_F ink by a factor of 1.3. Graphene Oxide was produced from natural graphite flakes. A chemical treatment was applied in order to produce graphene oxide through the Hummer’s method and Improved Hummer’s method. At the end of the process, the graphene oxide was recovered under form of colloidal suspensions. The characterization was made by Field Emission Scanning Electron Microscopy (FESEM), Ultraviolet–visible (UV-vis) spectroscopy, Fourier Transform Infrared spectroscopy (FTIR), Energy Dispersive Spectroscopy (EDS), and Raman Spectroscopy. The results showed a good level of oxidation in the material and small flakes of graphene oxide. Concerning to the adsorption process for drug delivery, a cancer drug was used. Doxorubicin (DOX) hydrochloride was placed in contact with GO to evaluate the capacity of adsorption of the material using the depletion method. The study was carried out by using different initial concentrations of DOX and different pH values. All experiments were placed under agitation in dark conditions at room temperature and different incubation times. Once the results of final concentrations was completed, the quantity loaded onto GO were calculated. Finally, the kinetic adsorption showed a percentage of 95% at pH 3 in only 24 hours of interaction. The GO presented excellent characteristics to be used in nano-medical applications. Regarding environmental applications, an adsorption study was conducted using commercial Acridine Orange dye (AO). The adsorption process was proved using the depletion method. AO was prepared in aqueous solution at different concentrations, and these were placed under agitation and dark conditions at different contact times to evaluate the kinetic adsorption. The GO was analyzed at different weight using the highest concentration of AO. On the other hand, the temperature and the incubation time were varied, to find out the best conditions for the adsorption process. The kinetic of adsorption showed a percentage of adsorption among 75% to 95% in the first 20 min for higher concentrations and GO showed a better adsorption process to higher temperatures
Preparazione di nuovi biomateriali: membrane zeolitiche ibride e cristalli per adsorbimento di farmaci di interesse oncologico
(2012-11-20) Riccio, Ilaria Iolanda; Sisci, Diego; Tavolaro, Adalgisa; Aquila, Saveria; Tavolaro, Palmira
Preparazione e caratterizzazione di nanomateriali carboniosi mediante processi idrotermali
(Università della Calabria, 2020-04-21) Veltri, Francesco; Caputi, Lorenzo; Tavolaro, Adalgisa; Ciuchi, Federica; Mazzulla, Alfredo