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Falco C.,Max Planck Institute for Colloids | Baccile N.,CNRS Laboratory of Condensed Matter Chemistry, Paris | Titirici M.-M.,Max Planck Institute for Colloids
Green Chemistry | Year: 2011

Hydrothermal carbonization (HTC) has demonstrated that it is an effective technique for the production of functionalized carbon materials from simple carbohydrates, such as monosaccharides and disaccharides. The chemical structure of the HTC carbon has been identified in detail by means of solid-state MAS 13C NMR investigations. However, it has not yet been clearly shown what the effects are of the processing temperature and time on the chemical structure and morphology of the generated HTC carbon. This study shows, with the help of SEM, elemental and yield analysis and solid-state MAS 13C NMR, the effects of these two key variables on the final nature of the produced material, allowing the development of a mechanistic model. According to the chosen set of processing parameters, the chemical structure of the HTC carbon can be tuned from polyfuran rich in oxygen containing functional groups to a carbon network of extensive aromatic domains. The same kind of investigation using lignocellulosic biomass as a carbon precursor shows a striking difference between the HTC mechanism of glucose and cellulose. The biopolymer, when it is treated under mild hydrothermal conditions (180-280 °C), tends to react according to a reaction scheme which leads to its direct transformation into an aromatic carbon network and which has strong similarities with classical pyrolysis. This journal is © The Royal Society of Chemistry. Source

Lei W.,Deakin University | Portehault D.,College de France | Portehault D.,CNRS Laboratory of Condensed Matter Chemistry, Paris | Liu D.,Deakin University | And 2 more authors.
Nature Communications | Year: 2013

Effective removal of oils, organic solvents and dyes from water is of significant, global importance for environmental and water source protection. Advanced sorbent materials with excellent sorption capacity need to be developed. Here we report porous boron nitride nanosheets with very high specific surface area that exhibit excellent sorption performances for a wide range of oils, solvents and dyes. The nanostructured material absorbs up to 33 times its own weight in oils and organic solvents while repelling water. The saturated boron nitride nanosheets can be readily cleaned for reuse by burning or heating in air because of their strong resistance to oxidation. This easy recyclability further demonstrates the potential of porous boron nitride nanosheets for water purification and treatment. © 2013 Macmillan Publishers Limited. All rights reserved. Source

Carenco S.,CNRS Laboratory of Condensed Matter Chemistry, Paris | Carenco S.,College de France
Chemistry - A European Journal | Year: 2014

Carbon monoxide is a ubiquitous molecule in surface science, materials chemistry, catalysis and nanotechnology. Its interaction with a number of metal surfaces is at the heart of major processes, such as Fischer-Tropsch synthesis or fuel-cell optimization. Recent works, coupling structural and nanoscale in situ analytic tools have highlighted the ability of metal surfaces and nanoparticles to undergo restructuring after exposure to CO under fairly mild conditions, generating nanostructures. This Minireview proposes a brief overview of recent examples of such nanostructuring, which leads to a discussion about the driving force in reversible and non-reversible situations. Nanoparticles and reactive surfaces: This Minireview provides an overview of selected CO-induced nanostructuring (see scheme). Recent examples of metal-surface and nanoparticle restructuring as a consequence of exposure to CO are discussed and show that nanoscale structures can be obtained under fairly mild conditions. Several cases of mono- and bimetallic compounds are described that show a range of behaviours in relation with the metal-CO interaction strength. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source

Tran-Thi T.-H.,CEA Saclay Nuclear Research Center | Dagnelie R.,CEA Saclay Nuclear Research Center | Crunaire S.,CEA Saclay Nuclear Research Center | Nicole L.,CNRS Laboratory of Condensed Matter Chemistry, Paris
Chemical Society Reviews | Year: 2011

Sol-gel porous materials with tailored or nanostructured cavities have been increasingly used as nanoreactors for the enhancement of reactions between entrapped chemical reactants. The domains of applications issued from these designs and engineering are extremely wide. This tutorial review will focus on one of these domains, in particular on optical chemical sensors, which are the subject of extensive research and development in environment, industry and health. © 2011 The Royal Society of Chemistry. Source

Lupan O.,CNRS Laboratory of Condensed Matter Chemistry, Paris | Pauporte T.,CNRS Laboratory of Condensed Matter Chemistry, Paris | Le Bahers T.,CNRS Laboratory of Condensed Matter Chemistry, Paris | Viana B.,Stefan Cel Mare University of Suceava | Ciofini I.,CNRS Laboratory of Condensed Matter Chemistry, Paris
Advanced Functional Materials | Year: 2011

The band-gap engineering of doped ZnO nanowires is of the utmost importance for tunable light-emitting-diode (LED) applications. A combined experimental and density-functional theory (DFT) study of ZnO doping by copper (Zn 2+ substitution by Cu2+) is presented. ZnO:Cu nanowires are epitaxially grown on magnesium-doped p-GaN by electrochemical deposition. The heterojunction is integrated into a LED structure. Efficient charge injection and radiative recombination in the Cu-doped ZnO nanowires are demonstrated. In the devices, the nanowires act as the light emitters. At room temperature, Cu-doped ZnO LEDs exhibit low-threshold emission voltage and electroluminescence emission shifted from the ultraviolet to violet-blue spectral region compared to pure ZnO LEDs. The emission wavelength can be tuned by changing the copper content in the ZnO nanoemitters. The shift is explained by DFT calculations with the appearance of copper d states in the ZnO band-gap and subsequent gap reduction upon doping. The presented data demonstrate the possibility to tune the band-gap of ZnO nanowire emitters by copper doping for nano-LEDs. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source

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