Consiglio Nazionale Interuniversitario Of Science Fisiche Della Materia

Rome, Italy

Consiglio Nazionale Interuniversitario Of Science Fisiche Della Materia

Rome, Italy
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Caruso T.,University of Calabria | Caruso T.,Consiglio Nazionale Interuniversitario Of Science Fisiche Della Materia | Castriota M.,University of Calabria | Castriota M.,Consiglio Nazionale Interuniversitario Of Science Fisiche Della Materia | And 13 more authors.
Applied Surface Science | Year: 2014

The electronic, morphological and structural properties of WO3 thin films, synthesized via a sol-gel route and deposited on ITO/glass substrates by spin-coating, were analyzed as a function of annealing temperature (100-700 C range) by Scanning Electron Microscopy, Atomic Force Microscopy, micro-Raman spectroscopy, X-ray Diffraction and Photoelectron Spectroscopy. We have found evidence of two competing processes when the film is annealed at high temperatures (600-700 C): a structural phase transition from amorphous to crystalline WO3 and a temperature-activated diffusion of sodium ions, from the substrate into the WO3 film, which induces the formation of sodium tungstate. The surface of the films was found to be oxygen deficient after deposition but reverted to fully oxidized WO3 after high temperature annealing in air. The annealing also induced a restructuring of the films with formation of nano-crystalline aggregates. The influence of film thickness on these processes was also investigated. © 2014 Elsevier B.V. All rights reserved.


Kwiatkowski M.,AGH University of Science and Technology | Policicchio A.,University of Calabria | Policicchio A.,Consiglio Nazionale Interuniversitario Of Science Fisiche Della Materia | Seredych M.,City College of New York | Bandosz T.J.,City College of New York
Carbon | Year: 2016

Adsorption of CO2 at temperatures close to ambient and up to 1.5 MPa was measured on nanoporous polymer-derived carbon, on its composite with reduced graphene oxide (rGO), and on their air oxidized counterparts. The isotherms were fitted by the LBET class models and the adsorption mechanisms were described in terms of parameters derived from the mentioned models including the amount adsorbed, adsorption energy distribution, maximum CO2 adsorption energy in the first layer, heterogeneity level parameter in the first adsorbed layer, cluster heights, and changes in the volume adsorbed in the first layer upon cycling experiments. The results were analyzed in conjunction with adsorbents' porosity and surface chemistry. Even though the volume of small pores is a main parameter governing the extent of the adsorption process, surface chemistry was found as important for the energetics of adsorption and for the clustering patterns the CO2 molecules in the pore system. Regarding the quantity and quality of surface species, the results suggest that the latter might have more dominant effect on the mechanism of the adsorption process. © 2015 Elsevier Ltd. All rights reserved.


Cazzanelli E.,University of Calabria | Cazzanelli E.,Consiglio Nazionale Interuniversitario Of Science Fisiche Della Materia | Caruso T.,University of Calabria | Caruso T.,Consiglio Nazionale Interuniversitario Of Science Fisiche Della Materia | And 8 more authors.
Journal of Raman Spectroscopy | Year: 2013

This work reports the peculiar properties of a graphene film prepared by the chemical vapor deposition of ethylene in high vacuum on a well oriented and carefully cleaned Pt(111) crystal surface maintained at high temperature. In-situ and ex-situ characterization techniques (low-energy electron diffraction, high-resolution electron energy loss spectroscopy, scanning electron microscopy and Raman micro-spectroscopy) used here indicate the prevalence of single-layer regions and the presence of two different orientations of the graphene sheets with respect to the Pt(111) substrate. In most of the deposited area, evidence is found of a compressive stress for the graphene lattice, as a net result of the growth process on a metal substrate. This graphene film grown on Pt(111) exhibits a lower degree of order and of homogeneity with respect to the exfoliated graphene on Si/SiO2, as it is found generally for graphene on metals, but several characterization techniques indicate a better quality than in previous deposition experiments on the same metal substrate. Copyright © 2013 John Wiley & Sons, Ltd.

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