306 research outputs found
Novel Pt-Ru nanoparticles formed by vapour deposition as efficient electrocatalyst for methanol oxidation, Part I. Preparation and physical characterization
No full textBimetallic Pt-Ru nanoparticles supported on carbon substrates have been prepared reproducibly by a simple method that utilizes commercially available metal-organic precursors at low temperature in vacuum. Particles morphology, composition and structure have been investigated using (HR)TEM, EDX, Selected Area Electron Diffraction (SAED) and powder XRD analysis. TEM shows that the obtained nanoparticles are homogeneously dispersed on the substrate surface and exhibit narrow size distribution, the average diameter being ca. 2nm. Point resolved EDX analysis demonstrates co-presence of both Pt and Ru in each particle, thereby indicating that truly bimetallic nanoparticles have been obtained. Moreover, EDX performed on several areas of the sample evidences uniform particles composition. The latter can be controlled very easily and effectively by regulating the operation temperature during particles preparation. HRTEM imaging shows that the particles possess crystalline structure. Both SAED and XRD analyses indicate presence of nanoparticles exhibiting structure consistent with that of a fcc Pt-Ru alloy. Besides the fcc alloy, an additional crystalline phase might also be present as noticed by SAED. These nanoparticles display electrocatalytic activity with regard to methanol oxidation as evidenced by cyclic voltammetry (CV)
DeSanctis, D. Torresi, A. Balletti. (2011). “Effetto dei parametri di saldatura GTAW sulla microstruttura della zona termicamente alterata e della zona fusa dell’acciaio P91”.
No full textShaping of foam-like materials through the use of a sonotrode
No full textShaping of Polystyrene and Polyurethane with traditional machining operations may create dust and debris, which are undesired consequences of the manufacturing techniques adopted. The proposed technology makes use of an ultrasound probe that compresses and heats the foam-like material and forms the desired shape. The paper presents the preliminary tests as a first step toward a full feasibility analysis of the new proposed technology
Potential applications of bioartificial polymeric membranes based on poly(vinyl alcohol) and sodium alginate for hemodialysis
No full textIntragranular Nucleation of Ferrite on Precipitates and Grain Refinement in a Hot Deformed V-microalloyed Steel
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Cerium(III) N,N-dibutylcarbamate as precursor to nanocrystalline cerium dioxide
No full textNanostructured ceria has been prepared in mild conditions by hydrolysis of the N,N-dibutylcarbamato
complex of cerium(III), [Ce(O2CNBu2)3], obtained by lanthanide extraction from aqueous solution into
heptane containing CO2 saturated NHBu2. In dependence of the hydrolysis conditions, cerium(III) carbonates
or hydroxocarbonate (characterized by IR, XRD and metal content) were obtained. Thermal treatment
of these products at relatively low temperature (200 C) yielded CeO2 in the form of a light
yellow powder. The structure and morphology of the samples were studied by TEM, FESEM and XRD
studies. The medium crystallite dimensions, estimated by TEM, appear to be of a few nanometers.
Ceria with smaller medium crystallite dimensions was obtained by increasing the amine concentration
in the course of the hydrolysis proces
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