Publications by authors named "Philippe Barboux"

5 Publications

  • Page 1 of 1

Prediction of Isoelectric Point of Manganese and Cobalt Lamellar Oxides: Application to Controlled Synthesis of Mixed Oxides.

Langmuir 2018 06 30;34(23):6670-6677. Epub 2018 May 30.

Chimie-ParisTech, PSL Research University, CNRS Institut de Recherche de Chimie-Paris (IRCP) , 75005 Paris , France.

To design novel layered materials, bottom-up strategy is very promising. It consists of (1) synthesizing various layered oxides, (2) exfoliating them, then (3) restacking them in a controlled way. The last step is based on electrostatic interactions between different layered oxides and is difficult to control. The aim of this study is to facilitate this step by predicting the isoelectric point (IEP) of exfoliated materials. The Multisite Complexation model (MUSIC) was used for this objective and was shown to be able to predict IEP from the mean oxidation state of the metal in the (hydr)oxides, as the main parameter. Moreover, the effect of exfoliation on IEP has also been calculated. Starting from platelets with a high basal surface area over total surface area, we show that the exfoliation process has no impact on calculated IEP value, as verified with experiments. Moreover, the restacked materials containing different monometallic (hydr)oxide layers also have an IEP consistent with values calculated with the model. This study proves that MUSIC model is a useful tool to predict IEP of various complex metal oxides and hydroxides.
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http://dx.doi.org/10.1021/acs.langmuir.8b00190DOI Listing
June 2018

Probing in situ the nucleation and growth of gold nanoparticles by small-angle X-ray scattering.

Nano Lett 2007 Jun 26;7(6):1723-7. Epub 2007 May 26.

LIONS, Service de Chimie Moléculaire, CEA Saclay, Bat. 125, F-91191 Gif-sur-Yvette Cedex, France.

We probe in situ by synchrotron SAXS/WAXS and UV-visible spectroscopy the nucleation and growth of gold nanoparticles. The use of a fast-mixing stopped-flow device enables the assessment of the whole particle formation process with a 200 ms time resolution. The number of particles, their size distribution, and the yield of the reaction is determined in real time through the quantitative analysis of the SAXS data on an absolute scale. Two ligands exhibit drastically different behaviors: when an alkanoic acid is used, a nucleation phase of 1 s is followed by a growth step whose rate is limited by the reaction of the monomers at the interface; on the other hand, when an alkylamine is used, the nucleation rate is increased by an order of magnitude, thus annealing growth by a lack of monomer and yielding R=1 nm particles in 2 s, as compared with R=3.7 nm in 12 s for the acid case.
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http://dx.doi.org/10.1021/nl0707149DOI Listing
June 2007

Modification of the surface properties of porous nanometric zirconia particles by covalent grafting.

Langmuir 2004 Apr;20(8):3449-55

Laboratoire de Physique de la Matière Condensée, CNRS UMR 7643C, Ecole Polytechnique, 91128 Palaiseau Cedex, France.

We here report on the covalent grafting of various phosphated species (phosphoric acid, phenylphosphonic acid, and octyl phosphate) onto the surface of monoclinic zirconia nanoparticles obtained by hydrothermal treatment of zirconium acetate. The initial particles are 60 nm aggregates of nanometric primary grains and present an inner porosity. Small-angle X-ray scattering shows that the high specific area of the colloidal particles (450 m2 x g(-1)) decreases to 150 m2 x g(-1) upon drying. Therefore, phosphated reactants can access the whole internal surface of the aggregates only before drying. The surface of the particles can be covered with functional groups bound through a variable number of Zr-O-P bonds. Several factors probably enhance the reaction between the particles and the phosphates or phosphonates: the large specific area of the particles, a fully accessible porous network, and a large concentration of surface terminal groups. At the same time, the morphology of the particles is well preserved upon grafting. This is due to the good crystallinity of the primary grains that constitute the particles. In addition, the grafting drastically modifies the surface properties of the colloids. For example, the polarizability of the particles decreases in the sequence -POH > as-prepared ZrO2 > -PC6H5 > -POC8H17. Furthermore, the grafting of octyl phosphate allows exclusion of water from pores of 2 nm radius, up to hydrostatic pressures of 20 MPa.
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http://dx.doi.org/10.1021/la036249mDOI Listing
April 2004

Octanuclear oxothiomolybdate(v) rings: structure and ionic-conducting properties.

Chemistry 2004 Jun;10(12):3026-32

Institut Lavoisier, IREM, Université de Versailles Saint-Quentin, 45 Avenue des Etats-Unis, UMR 8637, 78035 Versailles Cedex, France.

A family of alkali salts of octanuclear oxothiomolybdate rings has been synthesized by crystallization of the [Mo(8)S(8)O(8)(OH)(8)[HMO(5)(H(2)O)]](3-) (noted HMo(8)M(3-); M=Mo, W) and [Mo(8)S(8)O(8)(OH)(8)(C(2)O(4))](2-) (noted Mo(8)ox(2-)) anions in an aqueous solution of ACl (A=Li, Na, K, Rb). Single-crystal X-ray diffraction experiments have been performed showing that the alkali salts exhibit a similar three-dimensional structure. Disordered alkali ions form columns to which the anionic rings are anchored. Ionic-conductivity measurements on pressed pellets have revealed two different behaviors. The lithium salts of HMo(8)M(3-) (M=Mo, W) are moderately good proton conductors at room temperature (sigma=10(-5) S cm(-1)) and the profile of conductivity as a function of relative humidity shows that the conductivity is due to surface-proton motion (particle-hydrate-type mechanism). On the other hand, the lithium salt of Mo(8)ox(2-) competes with the best crystalline lithium conductors at room temperature (sigma=10(-3) S cm(-1)), and (7)Li NMR experiments confirm the mobility of the lithium ions along the one-dimensional channels of this material.
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http://dx.doi.org/10.1002/chem.200400068DOI Listing
June 2004

Synthesis, X-ray and neutron diffraction characterization, and ionic conduction properties of a new oxothiomolybdate Li3[Mo8S8O8(OH)8[HWO5(H2O)]] x 18H2O.

Chemistry 2002 Jan;8(2):349-56

Institut Lavoisier, IREM, UMR 8637, Université de Versailles Saint-Quentin, Versailles, France.

The new oxothiomolybdate anion [Mo8S8O8(OH)8[HWO5(H2O)]]3- (denoted HMo8W3-) has been synthesized in aqueous solution by an acido-basic condensation reaction. Four (Mo(V)2S2O2) building blocks are connected through hydroxo bridges around a central [W(VI)O6] octahedron. X-ray and neutron diffraction studies have been performed on single crystals of the lithium salt Li3[Mo8S8O8(OH)8[HWO5(H2O)]] x 18H2O (Li3HMo8W x 18H2O) in an aqueous grown from HMo8W3- solution of LiCl (1 M). The neutron diffraction experiment enabled us to locate both the protons and the lithium ions. In the structure of Li3HMo8W x 18H20, ring-shaped anions interleaved by a cluster of disordered hydrogen-bonded water molecules stack on top of each other along lithium pillars. The lithium columns are formed by alternating edge-sharing octahedra and tetrahedra, with one lithium site in four being totally vacant. Ionic conductivity measurements on pressed pellets have shown that Li3HMo8W x 18H2O is a good ionic conductor at room temperature (sigma = 10(-5) S cm(-1)), but the ionic conductivity on single crystals is smaller by two orders of magnitude and is isotropic; this suggests the main path of conduction involves surface protons rather than lithium ions of the bulk.
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http://dx.doi.org/10.1002/1521-3765(20020118)8:2<349::AID-CHEM349>3.0.CO;2-5DOI Listing
January 2002