In situ electrochemical X-ray spectromicroscopy investigation of the reduction/reoxidation dynamics of Ni-Cu solid oxide fuel cell anodic material in contact with a Cr interconnect in 2 ×10 -6 mbar O 2
Bozzini B.,Universital Salento |
Amati M.,Elettra - Sincrotrone Trieste |
Gregoratti L.,Elettra - Sincrotrone Trieste |
Kazemian M.,Elettra - Sincrotrone Trieste |
And 4 more authors.
Journal of Physical Chemistry C | Year: 2012
Following our systematic investigations on the durability of solid oxide fuel cell (SOFC) components (Bozzini, B.; Tondo, E.; Prasciolu, M.; Amati, M.; Kazemian, M.; Gregoratti, L.; Kiskinova, M. ChemSusChem, http://dx.doi.org/10. 1002/cssc.201100140), the present in situ scanning photoelectron microscopy study is focused on the redox behavior of Ni-Cu bilayers in contact with Cr, representing the anodic material and interconnects for SOFCs, respectively. The experiments with this model cell, using yttria-stabilized zirconia (YSZ) electrolyte, were carried out in 2 × 10 -6 mbar O 2 at 650 Â°C at open circuit potential (OCP) and under applied potential. The elemental images and the spectra from selected parts of the cell have revealed dramatic compositional and morphological changes under OCP conditions, yielding Ni-Cu islands covered with NiO in the electrode region and a NiO network in the YSZ electrolyte region. The Ni reduction dynamics as a function of applied potential is followed by continuous monitoring of the evolution of the Ni 2p spectra in different regions, which allowed the location of electrochemically active areas of the half-cell upon cathodic polarization. It was shown that after electrochemical reduction the reoxidation at OCP results in notable morphology alterations of the triple-phase contact region, which can be related to the empirically observed degradation of catalytic performance. © 2012 American Chemical Society.
Girardo S.,CNR Institute of Neuroscience |
Palpacelli S.,Numerical Methods Implimentation for Design of Industrial Applications NuMIDIA Srl |
Palpacelli S.,CNR Institute for applied mathematics Mauro Picone |
De Maio A.,Numerical Methods Implimentation for Design of Industrial Applications NuMIDIA Srl |
And 6 more authors.
Langmuir | Year: 2012
Flows in microcapillaries and associated imbibition phenomena play a major role across a wide spectrum of practical applications, from oil recovery to inkjet printing and from absorption in porous materials and water transport in trees to biofluidic phenomena in biomedical devices. Early investigations of spontaneous imbibition in capillaries led to the observation of a universal scaling behavior, known as the Lucas-Washburn (LW) law. The LW allows abstraction of many real-life effects, such as the inertia of the fluid, irregularities in the wall geometry, and the finite density of the vacuum phase (gas or vapor) within the channel. Such simplifying assumptions set a constraint on the design of modern microfluidic devices, operating at ever-decreasing space and time scales, where the aforementioned simplifications go under serious question. Here, through a combined use of leading-edge experimental and simulation techniques, we unravel a novel interplay between global shape and nanoscopic roughness. This interplay significantly affects the early-stage energy budget, controlling front propagation in corrugated microchannels. We find that such a budget is governed by a two-scale phenomenon: The global geometry sets the conditions for small-scale structures to develop and propagate ahead of the main front. These small-scale structures probe the fine-scale details of the wall geometry (nanocorrugations), and the additional friction they experience slows the entire front. We speculate that such a two-scale mechanism may provide a fairly general scenario to account for extra dissipative phenomena occurring in capillary flows with nanocorrugated walls. © 2012 American Chemical Society.
Pisanello F.,Italian Institute of Technology |
De Paolis R.,Universital Salento |
Lorenzo D.,Italian Institute of Technology |
Guardia P.,Italian Institute of Technology |
And 10 more authors.
ACS Applied Materials and Interfaces | Year: 2013
We show that assembled domains of magnetic iron-oxide nanoparticles (IONPs) are effective at increasing the dielectric permittivity of polydimethylsiloxane (PDMS) nanocomposites in the GHz frequency range. The assembly has been achieved by means of magnetophoretic transport and its efficacy, as well as the electromagnetic properties of the nanocomposite, has been found to depend on IONPs diameter. Remarkably, the dielectric permittivity increase has been obtained by keeping dielectric and magnetic losses very low, making us envision the suitability of nanocomposites based on aligned IONPs as substrates for radiofrequency applications. © 2013 American Chemical Society.
Lenucci M.S.,Universital Salento |
Durante M.,Universital Salento |
Anna M.,Universital Salento |
Dalessandro G.,Universital Salento |
Piro G.,Universital Salento
Journal of Agricultural and Food Chemistry | Year: 2013
This study provides information about the carbohydrate present in tomato pomace (skins, seeds, and vascular tissues) as well as in the byproducts of the lycopene supercritical carbon dioxide extraction (SC-CO2) such as tomato serum and exhausted matrix and reports their conversion into bioethanol. The pomace, constituting approximately 4% of the tomato fruit fresh weight, and the SC-CO2-exhausted matrix were enzyme saccharified with 0.1% Driselase leading to sugar yields of ∼383 and ∼301 mg/g dw, respectively. Aliquots of the hydrolysates and of the serum (80% tomato sauce fw) were fermented by Saccharomyces cerevisiae. The bioethanol produced from each waste was usually >50% of the calculated theoretical amount, with the exception of the exhausted matrix hydolysate, where a sugar concentration >52.8 g/L inhibited the fermentation process. Furthermore, no differences in the chemical solubility of cell wall polysaccharides were evidenced between the SC-CO2-lycopene extracted and unextracted matrices. The deduced glycosyl linkage composition and the calculated amount of cell wall polysaccharides remained similar in both matrices, indicating that the SC-CO2 extraction technology does not affect their structure. Therefore, tomato wastes may well be considered as potential alternatives and low-cost feedstock for bioethanol production. © 2013 American Chemical Society.