Ca3Co4O9+δ exhibits fast oxygen exchange kinetics rendering it a promising electrode for applicat... more Ca3Co4O9+δ exhibits fast oxygen exchange kinetics rendering it a promising electrode for application as an air electrode in solid oxide cells.
ABSTRACT Setting up antibacterial materials by nisin adsorption on surfaces depends mainly on the... more ABSTRACT Setting up antibacterial materials by nisin adsorption on surfaces depends mainly on the surface properties and the surface treatments allowing the modification of such properties. In order to investigate the factors affecting such adsorption, the native low density polyethylene (LDPE) was modified using Argon/Oxygen (Ar/O2) plasma, nitrogen (N2) plasma and plasma-induced grafting of acrylic acid (AA). The films were studied by various characterization techniques. The chemical surface modification was confirmed by X-ray photoelectron spectroscopy (XPS), the wettability of the surfaces was evaluated by contact angle measurements, the surface charge was determined by the zeta potential measurements, and the changes in surface topography and roughness were revealed by atomic force microscopy (AFM). Nisin was adsorbed on the native and the modified surfaces. The antibacterial activity, the nisin adsorbed amount, and the peptide distribution were compared for the four nisin-functionalized films. The highest antibacterial activity was recorded on the Ar/O2 followed by AA then by N2 treated films and the lowest activity was on the native film. The observed antibacterial activity was correlated to the type of the surface, hydrophobic and hydrophilic interactions, surface charge, surface topography, nisin adsorbed amount, and nisin distribution on the surfaces.
Aerogels and xerogels based on sulphated zirconia doped with nickel in the same atomic ratios S/Z... more Aerogels and xerogels based on sulphated zirconia doped with nickel in the same atomic ratios S/Zr = 0.5 and Ni/Zr = 0.1 have been synthesized by sol–gel method using two drying ways of the solvent in solid preparation steps. Aerogels obtained by drying in supercritical conditions of solvent stabilize zirconia tetragonal phase even at high calcination temperatures and present a developed surface area, whereas
Two series of WOx–CeO2 catalysts with a W content between 4.0 and 12 wt% prepared by coprecipitat... more Two series of WOx–CeO2 catalysts with a W content between 4.0 and 12 wt% prepared by coprecipitation (CW-PP) and impregnation (CW-IMP) of CeO2 were investigated with the aim of examining the role of tungsten and the support in acid-catalyzed reactions. The catalysts were characterized with several in situ techniques (XRD, Raman, XPS, and NH3-DRIFT), and nitrogen adsorption at 77 K. XRD
ABSTRACT Various PdO–support interactions could be obtained on the Pd/SiO2–Al2O3 catalyst prepare... more ABSTRACT Various PdO–support interactions could be obtained on the Pd/SiO2–Al2O3 catalyst prepared by the method adopted in this work. Higher palladium dispersion, lower palladium reduction temperature and better catalytic activity in methane combustion are obtained on the Pd/SiO2–Al2O3 catalyst when PdO–Si interaction is favoured than PdO–Al interaction. In addition, compared to the Pd/SiO2 and the Pd/Al2O3 catalysts, higher catalytic activity is obtained on the Pd/SiO2–Al2O3 solids due to their moderate acidity strength.
Oxide diffusion was studied in two innovative SOFC cathode materials, Ba2Co9O14 and Ca3Co4O9+δ de... more Oxide diffusion was studied in two innovative SOFC cathode materials, Ba2Co9O14 and Ca3Co4O9+δ derivatives. Although oxygen diffusion was confirmed in the promising material Ba2Co9O14, it was not possible to derive accurate transport parameters because of an oxidation process at the sample surface which has still to be clarified. In contrast, oxygen diffusion in the well-known Ca3Co4O9+δ thermoelectric material was improved when calcium was partly substituted with strontium, likely due to an increase of the volume of the rock salt layers in which the conduction process takes place. Although the diffusion coefficient remains low, interestingly, fast kinetics towards the oxygen molecule dissociation reaction were shown with surface exchange coefficients higher than those reported for the best cathode materials in the field. They increased with the strontium content; the Sr atoms potentially play a key role in the mechanism of oxygen molecule dissociation at the solid surface.
This paper reports a comparative kinetic investigation of the overall reduction of NO in the pres... more This paper reports a comparative kinetic investigation of the overall reduction of NO in the presence of CO or H2 over supported Pt-, Rh- and Pd-based catalysts. Different activity sequences have been established for the NO+H2 reaction Pt/Al2O3>Pd/Al2O3>Rh/Al2O3 and for the NO+CO reaction Rh/Al2O3>Pd/Al2O3> Pt/Al2O3. It was found that both reactions differ from the rate determining step usually ascribed to
Ca3Co4O9+δ exhibits fast oxygen exchange kinetics rendering it a promising electrode for applicat... more Ca3Co4O9+δ exhibits fast oxygen exchange kinetics rendering it a promising electrode for application as an air electrode in solid oxide cells.
ABSTRACT Setting up antibacterial materials by nisin adsorption on surfaces depends mainly on the... more ABSTRACT Setting up antibacterial materials by nisin adsorption on surfaces depends mainly on the surface properties and the surface treatments allowing the modification of such properties. In order to investigate the factors affecting such adsorption, the native low density polyethylene (LDPE) was modified using Argon/Oxygen (Ar/O2) plasma, nitrogen (N2) plasma and plasma-induced grafting of acrylic acid (AA). The films were studied by various characterization techniques. The chemical surface modification was confirmed by X-ray photoelectron spectroscopy (XPS), the wettability of the surfaces was evaluated by contact angle measurements, the surface charge was determined by the zeta potential measurements, and the changes in surface topography and roughness were revealed by atomic force microscopy (AFM). Nisin was adsorbed on the native and the modified surfaces. The antibacterial activity, the nisin adsorbed amount, and the peptide distribution were compared for the four nisin-functionalized films. The highest antibacterial activity was recorded on the Ar/O2 followed by AA then by N2 treated films and the lowest activity was on the native film. The observed antibacterial activity was correlated to the type of the surface, hydrophobic and hydrophilic interactions, surface charge, surface topography, nisin adsorbed amount, and nisin distribution on the surfaces.
Aerogels and xerogels based on sulphated zirconia doped with nickel in the same atomic ratios S/Z... more Aerogels and xerogels based on sulphated zirconia doped with nickel in the same atomic ratios S/Zr = 0.5 and Ni/Zr = 0.1 have been synthesized by sol–gel method using two drying ways of the solvent in solid preparation steps. Aerogels obtained by drying in supercritical conditions of solvent stabilize zirconia tetragonal phase even at high calcination temperatures and present a developed surface area, whereas
Two series of WOx–CeO2 catalysts with a W content between 4.0 and 12 wt% prepared by coprecipitat... more Two series of WOx–CeO2 catalysts with a W content between 4.0 and 12 wt% prepared by coprecipitation (CW-PP) and impregnation (CW-IMP) of CeO2 were investigated with the aim of examining the role of tungsten and the support in acid-catalyzed reactions. The catalysts were characterized with several in situ techniques (XRD, Raman, XPS, and NH3-DRIFT), and nitrogen adsorption at 77 K. XRD
ABSTRACT Various PdO–support interactions could be obtained on the Pd/SiO2–Al2O3 catalyst prepare... more ABSTRACT Various PdO–support interactions could be obtained on the Pd/SiO2–Al2O3 catalyst prepared by the method adopted in this work. Higher palladium dispersion, lower palladium reduction temperature and better catalytic activity in methane combustion are obtained on the Pd/SiO2–Al2O3 catalyst when PdO–Si interaction is favoured than PdO–Al interaction. In addition, compared to the Pd/SiO2 and the Pd/Al2O3 catalysts, higher catalytic activity is obtained on the Pd/SiO2–Al2O3 solids due to their moderate acidity strength.
Oxide diffusion was studied in two innovative SOFC cathode materials, Ba2Co9O14 and Ca3Co4O9+δ de... more Oxide diffusion was studied in two innovative SOFC cathode materials, Ba2Co9O14 and Ca3Co4O9+δ derivatives. Although oxygen diffusion was confirmed in the promising material Ba2Co9O14, it was not possible to derive accurate transport parameters because of an oxidation process at the sample surface which has still to be clarified. In contrast, oxygen diffusion in the well-known Ca3Co4O9+δ thermoelectric material was improved when calcium was partly substituted with strontium, likely due to an increase of the volume of the rock salt layers in which the conduction process takes place. Although the diffusion coefficient remains low, interestingly, fast kinetics towards the oxygen molecule dissociation reaction were shown with surface exchange coefficients higher than those reported for the best cathode materials in the field. They increased with the strontium content; the Sr atoms potentially play a key role in the mechanism of oxygen molecule dissociation at the solid surface.
This paper reports a comparative kinetic investigation of the overall reduction of NO in the pres... more This paper reports a comparative kinetic investigation of the overall reduction of NO in the presence of CO or H2 over supported Pt-, Rh- and Pd-based catalysts. Different activity sequences have been established for the NO+H2 reaction Pt/Al2O3>Pd/Al2O3>Rh/Al2O3 and for the NO+CO reaction Rh/Al2O3>Pd/Al2O3> Pt/Al2O3. It was found that both reactions differ from the rate determining step usually ascribed to
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