A5091120035- CO2 Reduction Techniques and Catalysts
- Graphene research and applications
- Electronic and Structural Properties of Oxides
- Ionic liquids properties and applications
- Advanced Electron Microscopy Techniques and Applications
- Electron and X-Ray Spectroscopy Techniques
- Magnetic properties of thin films
- 2D Materials and Applications
- Carbon Nanotubes in Composites
- Magnetic Properties and Synthesis of Ferrites
- Boron and Carbon Nanomaterials Research
- Characterization and Applications of Magnetic Nanoparticles
- Electrocatalysts for Energy Conversion
- Iron oxide chemistry and applications
- Nanoparticle-Based Drug Delivery
- Force Microscopy Techniques and Applications
- Advanced biosensing and bioanalysis techniques
- Gold and Silver Nanoparticles Synthesis and Applications
- Molecular Junctions and Nanostructures
- Carbon dioxide utilization in catalysis
- Microfluidic and Bio-sensing Technologies
- Microfluidic and Capillary Electrophoresis Applications
- Organic and Molecular Conductors Research
- Iron-based superconductors research
- Geomagnetism and Paleomagnetism Studies
Institut de minéralogie, de physique des matériaux et de cosmochimie
2014-2024
Sorbonne Université
2014-2024
Centre National de la Recherche Scientifique
2010-2024
Sorbonne University Abu Dhabi
2022
Institut de Recherche pour le Développement
2014-2020
Marie Curie
2016
Université Paris-Sud
2002-2008
Laboratoire de physique des Solides
2002-2008
Université Paris 8
2008
Université Paris-Saclay
2006
Spatially resolved electron energy loss spectroscopy experiments have been performed in an microscope on several individual boron nitride (BN) single-, double-, and triple-walled nanotubes, whose diameters number of shells carefully measured. In the low-loss region (from 2 to 50 eV) spectra analyzed within framework continuum dielectric theory, leading conclusion a weak influence out-of-plane contribution response tubes. The gap has measured be independent nanotubes geometry, close in-plane...
To investigate the dielectric response of isolated single-walled carbon nanotubes, (SWCNTs), spatially resolved electron energy-loss spectroscopy measurements have been carried out using a scanning transmission microscope in near-field geometry. Spectra compared with those acquired on multiwalled nanotubes (MWCNTs) made different numbers layers, and simulations performed within framework continuum theory, taking into account local anisotropic character these nanostructures adapted to...
Abstract Electroreduction of CO 2 to is one the simplest ways valorise as a source carbon. Herein, cheap, robust, Cu‐based hybrid catalyst consisting polymer Cu phthalocyanine coated on carbon nanotubes, which proved be selective for production (80 % faradaic yield) at relatively low overpotentials, was developed. Polymerisation shown have drastic effect selectivity reaction because molecular instead proton reduction under same conditions. Although material only showed isolated sites in...
Abstract Alloying strategies are commonly used to design electrocatalysts that take on properties of their constituent elements. Herein, such a strategy is develop Zn–Cu alloyed electrodes with unique hierarchical porosity and tunable selectivity for CO 2 versus H + reduction. By varying the Zn/Cu ratio, tailored syngas mixtures obtained without production other gaseous products, which attributed preferential CO‐ ‐forming pathways alloys. The ratios also significantly less sensitive applied...
Electrochemical CO2 reduction presents a sustainable route to the production of chemicals and fuels. Achieving narrow product distribution with heterogeneous Cu catalysts is challenging conventional material modifications offer limited control over selectivity. Here, we show that surface-immobilised molecular species can act as inhibitors for specific carbon products provide rational distributions. Combined experimental computational results showed anchoring thiol-functionalised pyridine on...
Abstract It is generally believed that CO 2 electroreduction to multi‐carbon products such as ethanol or ethylene may be catalyzed with significant yield only on metallic copper surfaces, implying large ensembles of atoms. Here, we report an inexpensive Cu‐N‐C material prepared via a simple pyrolytic route exclusively feature single atoms CuN 4 coordination environment, atomically dispersed in nitrogen‐doped conductive carbon matrix. This achieves aqueous at Faradaic 55 % under optimized...
Spatially resolved electron energy-loss spectroscopy (EELS) in a scanning transmission microscope (STEM) has been used to investigate as fluidic phase nanoubbles embedded metallic Pd90Pt10 matrix. Using the 1s->2p excitation of He atoms, maps distribution, particular its density an pressure bubbles different diameter have realized, thus providing indication involved bubble formation mechanism. However, short-range Pauli repulsion mechanism between electrons on neighboring atoms seems...
Exchange coupled nanoparticles that combine hard and soft magnetic phases are very promising to enhance the effective anisotropy while preserving sizes below 20 nm. However, core–shell structure is usually insufficient produce rare earth-free ferro(i)magnetic blocked at room temperature. We report on onion-type prepared by a three-step seed mediated growth based thermal decomposition method. The core@shell@shell consists of core an external shell Fe3−δO4 separated intermediate Co-doped...
We report on a systematic study of the structural, magnetic, and transport properties high-purity $1T$-${\mathrm{VS}}_{2}$ powder samples prepared under high pressure. The results differ notably from those previously obtained by deintercalating Li $\mathrm{Li}{\mathrm{VS}}_{2}$. First, no charge-density wave (CDW) is found transmission electron microscopy down to 94 K, though ab initio phonon calculations unveil latent CDW instability driven an acoustic softening at vector...
The synthesis and characterization of original ferrite multishell magnetic nanoparticles made a soft core (manganese ferrite) covered with two successive shells, hard one (cobalt then (nickel ferrite), are described. results demonstrate the modulation coercivity when new shells added.
We have analytically computed the energy-loss probability of a fast electron passing near locally anisotropic hollow nanotube, in nonretarded approximation. Numerical simulations been performed low loss (below 50 eV) region, and good agreement with experimental spatially resolved spectroscopy results is reported. also show importance surface coupling effect local anisotropy tubes for plasmonic response, extending conclusions previously reported spherical nano-objects.
We show how to prepare graphene samples on a glass substrate with the anodic bonding method. In this method, graphite precursor in flake form is bonded help of an electrostatic field and then cleaved off leave few layer substrate. Now that several methods are available for producing graphene, relevance our method its simplicity practicality about 100 µm lateral dimensions. This also extensible other layered materials. discuss some detailed aspects fabrication results from Raman spectroscopy,...
A general approach to model vibrational electron energy loss spectra obtained using an beam positioned away from the specimen is presented. The energy-loss probability of fast evaluated first-principles quantum mechanical calculations (density functional theory) dielectric response specimen. validity method assessed recently measured anhydrous β-guanine, important molecular solid used by animals produce structural colors. good agreement between theory and experiments lays basis for a...
Orientation-dependent aloof-beam vibrational electron-energy-loss spectroscopy is carried out on uniaxial icosahedral B_{12}P_{2} submicron crystals. We demonstrate that the high sensitivity of signal to crystal orientation allows for an unambiguous determination symmetry normal modes occurring at Brillouin zone center this anisotropic compound. The experimental results are assessed using first-principles quantum mechanical calculations (density functional theory) dielectric response...
Abstract The nanoscale distribution of magnetic anisotropies is measured in core@shell MnFe 2 O 4 @CoFe 7.0 nm particles using a combination element selective spectroscopies with different probing depths. As this picture not accessible by any other technique, emergent properties are revealed. coercive field constant whole nanospinel. very thin (0.5 nm) CoFe hard shell imposes strong anisotropy to the otherwise soft core: large gradient coercivity inside core lower values close interface...
A fast and straightforward strategy for thermopolymerization of polymer shells, at room temperature, a magnetic nanoparticle (MNP) surface under an alternating field (AMF) is presented. The polymerization triggered by the local heat generated MNPs when exposed to AMF polymerize organic shell around thermoactivation. This synthetic approach provides versatile MNP without macroscopic temperature increase, allowing efficient pathways magnetically induce single-layer-by-layer shells. method...
A series of exchange-coupled magnetic nanoparticles combining several phases in an onion-type structure were synthesized by performing a three-step seed-mediated growth process.
By means of high-pressure synthesis in the 4-6 GPa range, we report on successful growth high-quality 1T-V1+xS2 single crystals with controlled concentration, x = 0.09-0.17, self-intercalated V atoms van der Waals gap. A systematic X-ray diffraction and energy-dispersive spectroscopy study unveils a linear decrease pressure, dx/dP -0.042 GPa(-1), suggesting that stoichiometric (x 0) phase is stable above 8 GPa. Transmission electron microscopy electrical resistivity measurements show that,...
Hard ferrimagnetic CoFe<sub>2</sub>O<sub>4</sub> nanoparticles become softer in the presence of neighbouring soft MnFe<sub>2</sub>O<sub>4</sub> nanoparticles.
Abstract Electromagnetic response of individual boron nitride nanotubes (BNNTs) has been studied by spatially resolved electron energy loss spectroscopy (EELS). We demonstrate how dedicated EELS methods using subnanometer probes permit the analysis local dielectric properties a material on nanometer scale. The continuum model used to analyze low-loss EEL spectra recorded from these tubes. Using this model, we weak influence out-of-plane contribution BNNTs. optical gap, which can be deduced...
Colloidal solutions of magnetic nanoparticles (ferrofluids) exhibit intriguing macroscopic properties that find their origin in the dipole interparticle interactions taking place on nanoscale. Here, we study experimentally structuration and a ferrofluid composed 25 nm CoFe2O4 nanoflowers, which show different types nanoparticle assemblies with without an external field. A combination advanced magnetometry (first-order reversal curve measurements combined simulations), transmission electron...