Toward fully organic rechargeable charge storage devices based on carbon electrodes grafted with redox molecules

Activated carbon powders modified with naphthalimide and 2,2,6,6-tetramethylpiperidine-N-oxyl were assembled into a hybrid electrochemical capacitor containing an organic electrolyte. The fully organic rechargeable system demonstrated an increase in specific capacitance up to 51%, an extended operating voltage of 2.9 V in propylene carbonate, compared to 1.9 V for the unmodified system, and a power 2.5 times higher

Synthesis by the polyol process and ionic conductivity of nanostructured La2Mo2O9 powders

International audienceLa2Mo2O9 nanostructured powders were synthesized by the polyol process. The effects of the nature of the polyol, the refluxing time, the hydrolysis ratio, the metal concentration and the addition of hydroxide ions, on the purity and morphology of the powders are determined. Two main morphologies are observed, the particles being in the shape of platelets or spheres, with respectively diethylene glycol or ethylene glycol as solvent. A specific surface area of 24 m2/g was reached by varying the metal concentration. The conductivity measurements were recorded on pellets that present in some cases a closed porosity, the relative density reaching 95% without any milling step. According to the synthesis parameters, the grain conductivity can be slightly increased, the total conductivity remaining only slightly lower than that of pellets made of powders synthesized by solid state reaction

Rare Earth-Activated Silica-Based Nanocomposites

Two different kinds of rare earth-activated glass-based nanocomposite photonic materials, which allow to tailor the spectroscopic properties of rare-earth ions: (i) Er3+-activated SiO2-HfO2 waveguide glass ceramic, and (ii) core-shell-like structures of Er3+-activated silica spheres obtained by a seed growth method, are presented

Application of Cu-FAU nanozeolites for decontamination of surfaces soiled with the ESKAPE pathogens

Antimicrobial resistance is a global threat with catastrophic forecasts in terms of human and economic losses. The so-called ESKAPE pathogens (Enterococcus species, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumanii, Pseudomonas aeruginosa and Enterobacter species) represent a range of species of particular concern because they cause many serious hospital infections, and can show resistance toward available commercial antibiotics. Copper-containing zeolite nanocrystals (10e30 nm) with FAU-type structure (Cu-FAU), in the form of stable colloidal suspensions, were prepared at high yield in the absence of organic templates and studied for their activity against ESKAPE microorganisms. The materials were active against all six ESKAPE species. The survival of Staphylococcus aureus, Klebsiella pneumoniae and Pseudomonas aeruginosa on stainless-steel coupons after direct treatment with the CuFAU zeolite suspensions was determined quantitatively. Complete decontamination (5-log reduction in bacterial counts) was achieved within 20 min for P. aeruginosa, and within 10 min for the K. pneumoniae and S. aureus. This result is significant, particularly for sanitization of surfaces in healthcare settings, with the potential to initiate a new direction of research to help address the global antimicrobial resistance threat

Superconductivity up to 110 K in Bi2Sr2Ca2Cu3O10 compounds

In the Bi-Sr-Ca-Cu-O system, we have studied the compound with the ideal formula Bi2Sr2Ca2Cu3O10 , responsible for the superconductivity up to 110 K. The magnetic measurements reveal the presence of two phases in the samples with superconducting transitions up to 80 K and 110 K. By varying the composition and the thermal treatment of those samples, we have succeeded in increasing the amount of the superconducting phase with Tc up to 110 K. The Meissner effect reaches 30 % of - 3/8 π at 90 K for the undoped samples and more than 50 % for the samples doped with Pb. Because of the high reversibility of the magnetization versus magnetic field around Tc, we have evaluated the critical thermodynamic field. This one gives an electronic specific heat coefficient similar to the one of YBaCuO compounds.Nous avons étudié dans le système Bi-Si-Ca-Cu-O le composé responsable de la supraconductivité jusqu'à 110 K, de formule idéale Bi2Sr2Ca2Cu3O10. Les mesures d'aimantation montrent la présence de deux phases dans les échantillons, avec des transitions à 80 K et 110 K. En faisant varier la composition et les traitements thermiques de ces échantillons, nous avons réussi à augmenter la proportion de la phase supraconductrice jusqu'à 110 K. L'effet Meissner atteint 30 % de - 3/8 π à 90 K pour les échantillons non dopés et 50 % pour ceux dopés au plomb. La grande réversibilité des courbes d'aimantation en fonction du champ au voisinage de Tc nous a permis d'évaluer le champ critique thermodynamique. Celui-ci conduit à un coefficient de chaleur spécifique électronique similaire à celui des composés YBaCuO

Silver confined within zeolite EMT nanoparticles: preparation and antibacterial properties

The preparation of pure zeolite nanocrystals (EMT-type framework) and their silver ion-exchanged (Ag+-EMT) and reduced silver (Ag0-EMT) forms is reported. The template-free zeolite nanocrystals are stabilized in water suspensions and used directly for silver ion-exchange and subsequent chemical reduction under microwave irradiation. The high porosity, low Si/Al ratio, high concentration of sodium and ultrasmall crystal size of the EMT-type zeolite permitted the introduction of a high amount of silver using short ion-exchange times in the range of 2–6 h. The killing efficacy of pure EMT, Ag+-EMT and Ag0-EMT against Escherichia coli was studied semi-quantitatively. The antibacterial activity increased with increasing Ag content for both types of samples (Ag+-EMT and Ag0-EMT). The Ag0-EMT samples show slightly enhanced antimicrobial efficacy compared to that of Ag+-EMT, however, the differences are not substantial and the preparation of Ag nanoparticles is not viable considering the complexity of preparation steps

First Direct Synthesis by High Energy Ball Milling of a New Lanthanum Molybdate

International audienceHigh energy ball milling of mixtures of lanthanum and molybdenum oxides led to the in situ formation of a series of lanthanum molybdates, with a La:Mo ratio of 1:1 and various Mo oxydation states, depending on the vial and reacting materials. Among these molybdates, one had only been prepared through fused salt electrolysis previously, and another was not known up to now. This illustrates the relevance of ball milling as a potentially fruitful method to prepare new oxide compounds, The space group and cell parameters of the new lanthanum molybdate have been determined using electron and X-ray diffraction

Spark plasma texturing (SPT) of p-type [Ca2CoO3]0.62[CoO2] thermoelectric oxide

Hole-doped [Ca2CoO3]0.62[CoO2] (Co349) thermoelectric materials were densified and textured by spark plasma sintering (SPS) process. Thin pre-sintered Co349 lamellar samples were used to process textured monoliths. The textured thin monoliths were further used in obtaining samples with increased thickness for anisotropic property studies by hot-stacking as multiple layers. Infrared measurements were used to investigate the presence of carbon diffused from the SPS tool into the bulk of the sample. The phase compositions, grain texture, as well as microstructure of the samples were analyzed by X-ray diffraction and SEM studies. The high temperature thermoelectric transport properties of the bulk samples and the correlation between the grain orientations, structural and anisotropy of thermoelectric properties were discussed in detail. The textured sample processed by SPT shows the power factor value of 450 μW m-1 K-2 at 600 °C which is 30% higher than the corresponding value for SPS one and eight times larger than samples conventionally sintered. © 2016 Elsevier B.V. All rights reserved

Spark plasma texturing (SPT) of p-type [Ca2CoO3]0.62[CoO2] thermoelectric oxide

International audienceHole-doped [Ca2CoO3]0.62[CoO2] (Co349) thermoelectric materials were densified and textured by spark plasma sintering (SPS) process. Thin pre-sintered Co349 lamellar samples were used to process textured monoliths. The textured thin monoliths were further used in obtaining samples with increased thickness for anisotropic property studies by hot-stacking as multiple layers. Infrared measurements were used to investigate the presence of carbon diffused from the SPS tool into the bulk of the sample. The phase compositions, grain texture, as well as microstructure of the samples were analyzed by X-ray diffraction and SEM studies. The high temperature thermoelectric transport properties of the bulk samples and the correlation between the grain orientations, structural and anisotropy of thermoelectric properties were discussed in detail. The textured sample processed by SPT shows the power factor value of 450 μW m-1 K-2 at 600 °C which is 30% higher than the corresponding value for SPS one and eight times larger than samples conventionally sintered. © 2016 Elsevier B.V. All rights reserved

Oriented and polycrystalline NdNiO3 thin films on silicon substrate

International audienc