A mini organic redox-flow battery pluggable on the basis of a high-resolution nuclear magnetic resonance probehead has been conceived and built mainly by 3D printing. This device allows the realization of all modern spectroscopy experiments as well as imaging experiments. It has been tested for the real-time monitoring of redox cycling of 9,10-anthraquinone-2,7-disulfonic acid disodium salt (2,7-AQDS) in acidic conditions, which has revealed the preponderant role of dimerization in the processes of oxidation and reduction. Determination of the thermodynamic properties of homo- and heterodimer formation through quantum chemical, multilevel modeling workflows confirms our hypotheses about the molecular processes occurring during charge and discharge.

LiNi0.5Mn1.5O4 (LNMO) is a promising 5V-class electrode for Li-ion batteries but suffers from manganese dissolution and electrolyte decomposition owing to the high working potential. An attractive solution to stabilize the surface chemistry consists in mastering the interface between the LNMO electrode and the liquid electrolyte with a surface protective layer made from the powerful surface deposition method. Here, we show that a 7400 nm thick sputtered LNMO film coated with a nanometer-thick lithium-ion-conductive Li3PO4 layer was deposited by the atomic layer deposition method. We demonstrate that this "material model system" can deliver a remarkable surface capacity (∼0.4 mAh cm-2 at 1C) and exhibits improved cycling lifetime (×650%) compared to the nonprotected electrode. Nevertheless, we observe that mechanical failure occurs within the LNMO and Li3PO4 films when long-term cycling is performed. This in-depth study gives new insights regarding the mechanical degradation of LNMO electrodes upon charge/discharge cycling and reveals for the first time that the surface protective layer made from the ALD method is not sufficient for long-term stability applications.

In the current work, ultrasound irradiation is used to obtain nanocomposite materials by assembling fibrous clay minerals (sepiolite or palygorskite) and nanocellulose (cellulose nanofibers, CNF), which can be directly produced from microcrystalline cellulose (MCC) through high-shear mechanical and sonomechanical treatments in the presence of the silicate. In this process, the ultrasound energy, evaluated from 1 to 50 kJ, produces the fibrillation from the outer layers of MCC together with partial disintegration of the amorphous regions, leading to high aspect ratio cellulose nanofibers with diameter below 100 nm and variable length around 1 mu m. In the presence of sepiolite, a stable gel is formed due to the homogeneous dispersion of both organic and inorganic components, even at very low applied energies like 1 kJ. The generated biohybrid gels can be processed by solvent casting as self-standing films, which show an increase in the Young's modulus with respect to films of sonicated MCC alone, with the best results of 3.0 GPa for sepiolite loadings around 20-35% w/w. The ultrasound treatment produced also a strong decrease in the hydrophilicity of MCC when the applied energy was higher than 20 kJ, as determined from the corresponding water sorption isotherms. However, the applied energy does not affect the water sorption capacity of the nanocomposites containing sepiolite, showing similar isotherms for a given composition independently of the applied energy. The main difference among those nanocomposites is due to the sepiolite content, and thus, the isotherms corresponding to compositions with 20% w/w of sepiolite are closer to that of MCC alone. Those samples with low sepiolite loadings and prepared at applied energies of 20 kJ or higher also showed better water vapor transmission rates (WVTR). These results confirm that an optimal loading of 20% w/w sepiolite provided the lowest value of WVTR (286 g/m(2) day) in comparison to nanocomposites with higher sepiolite content, while keeping good mechanical properties (Young's modulus of 2.8 GPa). This is an easy methodology for preparation of nanocellulose/fibrous clay minerals composite materials that allows the further incorporation of other functional nanoparticles such as carbon nanotubes, to obtain in this case biohybrid materials provided with electrical conductivity.

Here we report the low-defect synthesis of bilayer graphene film on SiO2 with a nickel catalyst using pulsed laser deposition combined with rapid thermal annealing. A parametric study was performed with various initial amorphous carbon (a-C) film thicknesses and annealing temperatures and a fixed nickel catalyst film thickness. Raman spectra and mapping over large areas of up to 100 x 100 mu m(2) were used to investigate the structure and the defects of graphene films. Optimal conditions for graphene growth were an initial a-C film thickness of 2 nm and an annealing temperature of 900 degrees C. Results showed that 76% of the optimized film contained graphene bilayers, and 18% of the optimized film contained graphene monolayers. A transmittance of 87% at 550 nm is observed without any transfer process from the SiO2 substrate. This paper presents experimental guidelines for optimal synthesis conditions to control graphene growth by pulsed laser deposition.

Graphene-based materials are widely studied to enable significant improvements in electroanalytical devices requiring new generations of robust, sensitive and low-cost electrodes. In this paper, we present a direct one-step route to synthetize a functional nitrogen-doped graphene film onto a Ni-covered silicon electrode substrate heated at high temperature, by pulsed laser deposition of carbon in the presence of a surrounding nitrogen atmosphere, with no post-deposition transfer of the film. With the ferrocene methanol system, the functionalized electrode exhibits excellent reversibility, close to the theoretical value of 59 mV, and very high sensitivity to hydrogen peroxide oxidation. Our electroanalytical results were correlated with the composition and nanoarchitecture of the N-doped graphene film containing 1.75 at % of nitrogen and identified as a few-layer defected and textured graphene film containing a balanced mixture of graphitic-N and pyrrolic-N chemical functions. The absence of nitrogen dopant in the graphene film considerably degraded some electroanalytical performances. Heat treatment extended beyond the high temperature graphene synthesis did not significantly improve any of the performances. This work contributes to a better understanding of the electrochemical mechanisms of doped graphene-based electrodes obtained by a direct and controlled synthesis process.

Nanometer-sized structures, surfaces and sub-surface phenomena have played an enormous role in science and technological applications and represent a driving-force of current interdisciplinary science. Recent developments include the atomic-scale characterization of nanoparticles, molecular reactions at surfaces, magnetism at the atomic scale, photoelectric characterization of nanostructures as well as two-dimensional solids. Research and development of smart nanostructured materials governed by their surface properties is a rapidly growing field. The main challenge is to develop an accurate and robust electronic structure description. The density of surface-related trap states is analyzed by transient UV photoconductivity and temperature-dependent admittance spectroscopy. An advanced application of thin films on shaped substrates is the deposition of catalytic layers on hollow glass microspheres for hydrogen storage controlled exothermal hydrolytic release. Surface properties of thin films including dissolution and corrosion, fouling resistance, and hydrophilicity/hydrophobicity are explored to improve materials response in biological environments and medicine. Trends in surface bio-functionalization routes based on vacuum techniques, together with advances in surface analysis of biomaterials, are discussed. Pioneering advances in the application of X-ray nanodiffraction of thin film cross-sections for characterizing nanostructure and local strain including in-situ experiments during nanoindentation are described. Precise measurements and control of plasma properties are important for fundamental investigations and the development of next generation plasma-based technologies. Critical control parameters are the flux and energy distribution of incident ions at reactive surfaces; it is also crucial to control the dynamics of electrons initiating non-equilibrium chemical reactions. The most promising approach involves the exploitation of complementary advantages in direct measurements combined with specifically designed numerical simulations. Exciting new developments in vacuum science and technology have focused on forward-looking and next generation standards and sensors that take advantage of photonics based measurements. These measurements are inherently fast, frequency based, easily transferrable to sensors based on photonics and hold promise of being disruptive and transformative. Realization of Pascal, the SI unit for pressure, a cold-atom trap based ultra-high and extreme high vacuum (UHV and XHV) standard, dynamic pressure measurements and a photonic based thermometer are three key examples that are presented.

ANTARES beamline (BL), operating at very low photon energies, is a new soft X-ray scanning microscope recently built at SOLEIL Synchrotron, that offers a spectroscopic non-destructive nano-probe to study advanced materials. It combines a set of Fresnel Zone Plates (FZP) able to focalize the beam spot up to a few tenths of nanometres with a stable and precise sample nanopositioning (<1 nm). High energy-, angular- and spatial- resolution allow accurate electronic and chemical imaging combining angle-resolved photoelectron spectroscopy (NanoARPES or k-nanoscope) and core level detection by using both photoemission and X-ray absorption. Here, we report our latest results related to the optimization of the post-focusing mirrors system as well as its impact on the ultimate spatial resolution of the whole microscope.

Dans le cadre de ses missions de centre national de production et d’exploitation de lumière synchrotron au service de la recherche et de l’industrie, le Synchrotron SOLEIL a progressivement développé depuis son début d’activité en janvier 2008 une offre complète d’équipements, de compétences et de services en direction des industriels du secteur cosmétique.