Search results for "Material chemistry"
showing 10 items of 413 documents
Gas sensing properties of multiwall carbon nanotubes decorated with rhodium nanoparticles
2011
International audience; In the present work, multiwalled carbon nanotubes were decorated with rhodium nanoparticles using a colloidal solution in the post-discharge of an RF atmospheric plasma of argon (Ar) or argon/oxygen (Ar:O 2). The properties of these hybrid materials towards the room temperature detection of NO 2 , C 2 H 4 , CO, C 6 H 6 and moisture were investigated and discussed in view of compositional and morphological studies. It was found that the presence of oxygen in the plasma treatment is essential to significantly enhance the gas response of Rh-decorated multiwalled carbon nanotubes and to avoid response saturation even at low gas/vapor concentrations. These desirable effec…
Te-As-Se glass microstructured optical fiber for the middle infrared
2009
International audience; We present the first fabrication, to the best of our knowledge, of chalcogenide microstructured optical fibers in Te-As-Se glass, their optical characterization, and numerical simulations in the middle infrared. In a first fiber, numerical simulations exhibit a single-mode behavior at 3.39 and 9.3 μm, in good agreement with experimental near-field captures at 9.3 μm. The second fiber is not monomode between 3.39 and 9.3 μm, but the fundamental losses are 9 dB/m at 3:39 μm and 6 dB/m at 9.3 μm. The experimental mode field diameters are compared to the theoretical ones with a good accordance.
Magnesium(II) polyporphine: The first electron-conducting polymer with directly linked unsubstituted porphyrin units obtained by electrooxidation at …
2010
Abstract Electrooxidation of magnesium(II) porphine, a totally unsubstituted porphyrin, in acetonitrile solution under potentiostatic or potentiodynamic regime leads to a polymer film at the electrode surface. Polymer deposition takes place at extremely low potential, several hundred mV less positive even compared to the deposition potential for pyrrole or EDOT (at identical monomer concentrations) in the same solvent. Film thickness can be controlled by the passed deposition charge. This material and its THF-soluble fraction have been characterized by various electrochemical methods as well as by UV–visible and IR spectroscopies, XPS, XRD and MALDI-TOF techniques. This analysis has allowed…
Influence of Nitrogen Doping on Device Operation for TiO 2 -Based Solid-State Dye-Sensitized Solar Cells: Photo-Physics from Materials to Devices
2016
International audience; Solid-state dye-sensitized solar cells (ssDSSC) constitute a major approach to photovoltaic energy conversion with efficiencies over 8% reported thanks to the rational design of efficient porous metal oxide electrodes, organic chromophores, and hole transporters. Among the various strategies used to push the performance ahead, doping of the nanocrystalline titanium dioxide (TiO 2) electrode is regularly proposed to extend the photo-activity of the materials into the visible range. However, although various beneficial effects for device performance have been observed in the literature, they remain strongly dependent on the method used for the production of the metal o…
Hackmanite—The Natural Glow-in-the-Dark Material
2020
“Glow-in-the-dark” materials are known to practically everyone who has ever traveled by airplane or cruise ship, since they are commonly used for self-lit emergency exit signs. The green afterglow, persistent luminescence (PeL), is obtained from divalent europium doped to a synthetic strontium aluminate, but there are also some natural minerals capable of afterglow. One such mineral is hackmanite, the afterglow of which has never been thoroughly investigated, even if its synthetic versions can compete with some of the best commercially available synthetic PeL materials. Here we combine experimental and computational data to show that the white PeL of natural hackmanite is generated and cont…
Epoxy composites filled with high surface area-carbon fillers
2013
Citation: J. Appl. Phys. 114, 164304 (2013); doi: 10.1063/1.4826529 (Received 24 July 2013; accepted 6 October 2013; published online 22 October 2013) A comprehensive analysis of electrical, electromagnetic (EM), mechanical, and thermal properties of epoxy resin composites filled with 0.25–2.0 wt. % of carbon additives characterized by high surface area, both nano-sized, like carbon nanotubes (CNTs) and carbon black (CBH), and micro-sized exfoliated graphite (EG), was performed. We found that the physical properties of both CNTs- and CBH-based epoxy resin composites increased all together with filler content and even more clearly for CBH than for CNTs. In the case of EG-based composites, go…
Solution precursor plasma spray process as an alternative rapid one-step route for the development of hierarchical ZnO films for improved photocataly…
2018
Abstract The development of efficient photocatalytic hierarchical coral-like ZnO films via a relatively simple, efficient, rapid and single-step process is essential for industrial development. Herein, we report a novel method for directly synthesizing well-shaped ZnO nanorods (NRs) by Solution Precursor Plasma Spray (SPPS) process rather than conventional spherical/ellipsoidal particles. In the prepared ZnO-NRs films, the ZnO NRs display an average diameter of 190 nm, and exhibit a preferential orientation growth along (002) plane compared to a reference ZnO films (called ZnO-P) containing spherical/ellipsoidal particles. ZnO-NRs films exhibit relative narrower bandgap (3.02 eV) probably d…
Maximum Noble-Metal Efficiency in Catalytic Materials: Atomically Dispersed Surface Platinum
2014
International audience; Platinum is the most versatile element in catalysis, but it is rare and its high price limits large-scale applications, for example in fuel-cell technology. Still, conventional catalysts use only a small fraction of the Pt content, that is, those atoms located at the catalyst's surface. To maximize the noble-metal efficiency, the precious metal should be atomically dispersed and exclusively located within the outermost surface layer of the material. Such atomically dispersed Pt surface species can indeed be prepared with exceptionally high stability. Using DFT calculations we identify a specific structural element, a ceria ``nanopocket'', which binds Pt2+ so strongly…
Continuous hydrothermal synthesis of nanometric BaZrO3 in supercritical water
2007
Abstract Nanocrystalline barium zirconate (BaZrO 3 ) was synthesized using a hydrothermal synthesis process working in supercritical conditions and in a continuous way. By this method, we succeeded in the continuous and rapid production of nanopowders. As a preliminary work three barium precursors have been investigated: barium hydroxide (Ba(OH) 2 ), barium acetate (Ba(CH 3 COO) 2 ) and barium nitrate (Ba(NO 3 ) 2 ). Two of them (Ba(CH 3 COO) 2 and Ba(NO 3 ) 2 ) led to the pure perovskite phase. Then an experimental design has been conducted in order to determine the influence of the experimental parameters on the crystallinity and the grain size of the final product.
Mesoporous ZnFe2O4@TiO2 Nanofibers Prepared by Electrospinning Coupled to PECVD as Highly Performing Photocatalytic Materials
2017
International audience; Zinc ferrite @ titanium dioxide (ZnFe2O4@TiO2) composite nanofibers were elaborated by combining the two different techniques: electrospinning and plasma-enhanced chemical vapor deposition (PECVD). The nanofiber compositions were controlled using different ratios of zinc to iron. Their structural, morphological, and optical properties were analyzed by scanning electron microscopy, X-ray diffraction, energy-dispersive X-ray spectroscopy, BET surface area, Raman spectroscopy, and UV–visible spectrophotometry. The photocatalytic activity has been investigated by the degradation of methylene blue under visible light. The results indicate that the combination of spinel st…