sophiecarenco

We designed a low-temperature synthetic route for CeO₂ nanorods. We employed near-ambient-pressure X-ray photoelectron spectroscopy to monitor the cerium surface oxidation state during the initial annealing of the nanopowder, followed by exposure to a moderate pressure of H₂. We demonstrate that H₂ homolytic splitting at cerium sites is the main activation process at 100 °C, leading to the oxidation of 30% of the surface cerium atoms, while the H₂ splitting at oxygen sites was absent.

R. F. André, J.-J. Gallet, F. Bournel, S. Carenco, ChemCatChem 2024, DOI 10.1002/cctc.202400163.

We show that phosphines with adequate steric hindrance (e.g., PnBu₃ and PiBu₃) lower the onset temperature for phenylacetylene hydrogenation by nickel NPs under 7 bar of H₂, by ca 10 to 20 °C depending on the NP diameter. This result is of conceptual value because the hydrogenation may have been driven by the frustrated Lewis pair (FLP) between the Lewis basic phosphine and the Lewis acid nickel surface, forming a so-called “NanoFLP”. Moreover, we demonstrated that less than 2 phosphines per Ni surface atom are enough for the effect to arise. We showed that other terminal alkynes, like 1-octyne, can be hydrogenated with this method.

K. Azouzi, A. Ropp, S. Carenco, ACS Catalysis 2024, DOI 10.1021/acscatal.4c00054.

We report the positive effect of phosphine additives on the activity of cobalt phosphide nano-urchins for the semi-hydrogenation of phenylacetylene. While the nanocatalyst's activity was low under mild conditions (7 bar of H₂, 100 °C), the addition of a catalytic amount of phosphine remarkably increased the conversion, e. g., from 13 % to 98 % in the case of PⁿBu₃. A stereo-electronic map was proposed: the strongest effect was observed for low to moderately hindered phosphines, associated with strong electron donor abilities.

A. Ropp, R. F. André, S. Carenco, ChemPlusChem 2023, DOI 10.1002/cplu.202300469.

While the literature contains tens of protocols to prepare cerium oxide nanoparticles from Ce(III) precursors, there is still an open question regarding the time at which the cerium oxidation occurs and the role of hydroxide phases in this process. This article identifies an oxyhydroxide phase of Ce(IV) of the chemical formula CeO(OH)₂ as a key intermediate and proposes a crystal structure for it.

R. F. André, G. Rousse, C. Sassoye, M. Avdeev, B. Lassalle-Kaiser, B. Baptiste and S. Carenco, Chem. Mater. 2023, DOI 10.1021/acs.chemmater.3c00486.

NiCo nanoparticles are active catalysts at room temperature for Si−H bond activation. We designed nanoparticles with a nickel core and a limited amount of cobalt surface sites to clarify which of the two metals was the active site and if the neighbouring atoms influenced the reaction efficiency. The trend in catalytic activity is consistent with cobalt being the active site, and it shows a higher activity when its immediate neighbours are cobalt atoms.

A. Ropp, S. Carenco, ChemCatChem 2023, DOI 10.1002/cctc.202300400.

Here, we studied the organocatalyzed hydrosilylation of benzaldehyde with a phosphine, introduced at 10 mol %, and phenylsilane at room temperature. The best results of the screening over 13 phosphines and phosphites were obtained with linear trialkylphoshines (PMe₃, PnBu₃, POct₃), indicating the importance of their nucleophilicity. The products of the hydrosilylation were identified, allowing a monitoring of the concentration in the different species.

R. F. André, A. Palazzolo, C. Poucin, F. Ribot, S. Carenco, ChemPlusChem 2023, doi 10.1002/cplu.202300038

We developed here thin films of lanthanide oxysulfide, of optical quality by dip coating. As a model compound in the family of oxysulfides, (Gd,Ce)₂O₂S anisotropic nanoplates were used. The band gap of the materials was preserved through the deposition process. The thickness of the films was tuned in a broad range, from a few nanometers to 150 nm, using different concentrations of the colloidal suspensions and single-layer and multilayer deposition. Lastly, thermal treatment of the thin films was optimized to remove the stabilizing organic ligands of the nanoparticles while preserving their integrity.

L. Meyniel, C. Boissière, N. Krins, S. Carenco, Langmuir 2023, 39, 728-738, doi 10.1021/acs.langmuir.2c02026

We investigated here crystalline nickel carbide nanoparticles as catalysts in colloidal suspension for hydrogenation reactions under H₂ (7 bar) and below 100°C. Polar solvents appeared comparatively more favorable than less polar ones for the hydrogenation of two model substrates: nitrobenzene and phenylacetylene. Furthermore, the presence of water in the solvent mix was mostly favorable to the hydrogenation yield. We expanded the scope to a variety of aldehydes, ketones, esters, nitriles and unsaturated hydrocarbons.

R. F. André, L. Meyniel, S. Carenco, Cat. Sci. Tech. 2022, doi 10.1039/D2CY00894G

Due to the variety of cobalt crystallographic phases, forming fcc nanoparticles rather than phase mixture is a challenging endeavor. We found optimized conditions to form size-controlled fcc NiCo nanoparticles from preformed Ni nanoparticles. We then investigated the early stages of Co nucleation on the nickel using a lower stoichiometry of Co, down to 0.05 equiv. vs. Ni. We showed that cobalt reacts first on the nickel nanoparticles but easily forms cobalt-rich larger aggregates in the further steps of the reaction.

A. Palazzolo, C. Poucin, A. P. Freitas, A. Ropp, C. Bouillet, O. Ersen, S. Carenco, Nanoscale 2022, doi 10.1039/D2NR00917J.

Acceptability and relevance of nanoparticles in the society is greatly improved using a safer-by-design strategy. However, this is difficult to implement when nanoparticles are already on the market We employ this strategy for emerging nanoparticles of lanthanide oxysulfide, relevant for photocatalysis as well as for multimodal imaging. We investigated the production of reactive oxygen species (ROS) as a function of cerium content, in abiotic conditions and in vitro using murine macrophage RAW 264.7 cell line. We propose a risk analysis for lanthanide oxysulfide nanoparticles, leading to a technology assessment that fulfills the safer-by-design strategy.

A.-M. Nguyen, A. E. Pradas del Real, O. Durupthy, S. Lanone, C. Chanéac, S. Carenco, Nanomaterials 2022, 12, 422.

We propose the concept of a NanoFLP in a colloidal solution where one partner is a phosphine Lewis base and the other is the Lewis acid surface of a NiCo nanoparticle. We attempt to apply this concept to the hydrosilylative reduction of benzaldehyde. We identify a correlation between the Tolman cone angle and the silane conversion, consistent with both mechanisms; however, we found no clear correlation between the Tolman electronic parameter and the reaction outcome. Structural analyses evidenced that the nanoparticles are not altered during the reaction, which led us to propose the formation of a NanoFLP as a transient species in solution.

A. Palazzolo, S. Carenco. Chem. Mater. 2021, acs.chemmater.1c03105.

X-ray absorption near-edge structure (XANES) is a particularly well-adapted technique to study the L_2,3-edges of Mo (2520–2625 eV). It provides information on both the electronic and local structures of metal-containing species and allows drawing structure–activity relationships. However, L_2,3-edges are difficult to interpret, especially for 4d and 5d transition metals. In this work, we provide a method for their interpretation based on a library of spectra of simple Mo compounds. We suggest using the L₃-edge to determine the oxidation state and the L₂-edge to gain insight on the geometry around Mo atoms. This method is then applied to a series of molybdenum sulfide compounds to rationalize their structures.

A.P. Freitas, R. F. André, C. Poucin, T. K.-C. Le, J. Imbao, B. Lassalle-Kaiser, S. Carenco. Guidelines for the Molybdenum Oxidation State and Geometry from X-Ray Absorption Spectroscopy at the Mo L_2,3-Edges. J. Phys. Chem. C 2021, 10.1021/acs.jpcc.1c01875.

Transition metal carbides (TMCs) have attracted great interest due to their mechanical and catalytic properties but their syntheses generally require energy-consuming processes with temperatures above 800 °C. We report here a solid-state metathesis reaction between metal chlorides (ZrCl₄, NbCl₅, MoCl₃, MoCl₅, HfCl₄, TaCl₅, WCl₆) and potassium dispersed in carbon. Within seconds, it produces carbide or metallic nanoparticles of diameter below 50 nm supported on carbon. Based on thermodynamic and kinetic considerations, we propose a mechanism explaining the coexistence of several phases (metal, carbide, hydride) and their occurrence at each step of the reaction.

R. F. André, F. D'Accriscio, A. P. Freitas, G. Crochet, C. Bouillet, M. Bahri, O. Ersen, C. Sanchez, S. Carenco, Green Chem., 2021, 10.1039/D1GC01097B

Copper nanoparticle synthesis was studied by thorough characterization of the organic reactions happening during the synthesis. The reduction of copper(II) acetate by oleylamine resulted in a high amount of water and few by-products while the reduction of copper(II) acetylacetonate resulted in a low amount of water and many products. The nanoparticles showed different abilities to further dehydrogenate and transaminate oleylamine in the synthesis reaction pot. This was explained by the presence of a copper oxide phase in the nanoparticles prepared from copper acetate.

A. Pesesse, S. Carenco, Cat. Sci. Tech.., 2021, 10.1039/D1CY00639H.

Interlayer silylation of layered sodium octosilicate (Na-Oct) with various organoalkoxysilanes was conducted using hexadecyltrimethylammonium ion-exchanged layered octosilicate as an intermediate in the presence or absence of tetrabutylammonium fluoride (TBAF). The degree of silylation was increased by adding TBAF. It is suggested that fluoride ions perform a nucleophilic attack on the alkoxysilanes, which promotes the silylation reaction.Several functional groups were grafted with this procedure. Overall TBAF appears as a relevant catalyst for the covalent interlayer surface modification of layered silicates with organic functional groups.

M. Yatomi, M. Koike, N. Rey, Y. Murakami, S. Saito, H. Wada, A. Shimojima, D. Portehault, S. Carenco, C. Sanchez, C. Carcel, M. Wong Chi Man and K. Kuroda, Eur. J. Inorg. Chem., 2021, ejic.202100050.

We report the synthesis of air-stable P₄(MesCO)₄. We used it to prepare FeP and Fe₂P nanoparticles at 250 °C. X‐Ray photoelectron spectroscopy (XPS) and atomic pair distribution function (PDF) reveal the local order and bonding in the amorphous and crystalline materials. Crystalline FeP forms via an intermediate amorphous phase with a local order similar to that of the crystalline sample. We explore the electrocatalytic properties for the hydrogen evolution reaction (HER) in acidic and neutral electrolytes. In both electrolytes, amorphous FeP is a more efficient catalyst than crystalline FeP and Fe₂P.

F. D’Accriscio, E. Schrader, C. Sassoye, M. Selmane, R. F. André, S. Lamaison, D. Wakerley, M. Fontecave, V. Mougel, G. Le Corre, H. Grützmacher, C. Sanchez, S. Carenco, ChemNanoMat 2020, cnma.202000198.2020, doi:10.1002/cnma.202000198

Alkali cations are required for the colloidal synthesis of Ln₂O₂S nanoplates in organic solvent. We challenge the commonly accepted scenario of partial lanthanide substitution by the alkali. We demonstrate the formation of an alkali-stabilized oleate mesophase acting as a template for nanoparticle nucleation and growth.

C. Larquet, D. Carriere, A.-M. Nguyen, T. K.-C. Le, X. Frogneux-Plé, I. Génois, P. Le Griel, A. Gauzzi, C. Sanchez, S. Carenco, Chem. Mater. 2020, doi:10.1021/acs.chemmater.9b04059

This review summarizes the syntheses and applications of metal oxysulfides. Bulk compounds of rare earth and transition metals are discussed in the section Introduction. After a presentation of their main properties and applications, their structures are presented and their syntheses are discussed. The section Bulk Materials and Their Main Applications is dedicated to the growing field of nanoscaled metal oxysulfides. Lanthanide-based nanoparticles are discussed first, followed by transition-metal based nanoparticles.

C. Larquet, S. Carenco, Frontiers in Chem. 2020, doi:10.3389/fchem.2020.00179

Surface and core of inorganic nanoparticles may undergo profound transformations in their environment of use. Accurate description is key to understand and control surface reactivity.

Through a selection of case studies, this feature article proposes a journey from surface science to nanoparticle design, while illustrating state-of-the-art spectroscopies that help provide a relevant description of inorganic nanoparticles in the context of surface reactivity.

S. Carenco, Chem. Commun. 2018, 54, 6719-6727

This Personal Account is about the design, synthesis and monitoring of metal alloy nanoparticles.

Nanoalloys represent a playground to establish structure-properties relationships within the nano-matter. The rational design of nanoalloys is discussed (reactants choice, composition control), in relation with their surface state. Consequences on heterogeneous and homogeneous catalytic reactions, as well as for energy storage and conversion, is illustrated through examples.

S. Carenco, Chem. Rec. 2018, 18, 1114-1124

In this extensive review, we discuss about the synthesis, properties and applications of metal phosphide and metal borides nanoparticles. We show the similarities between these two classes of compounds. We comment on the trends of the field as well as on the latest advances.

S. Carenco, D. Portehault, C. Boissière, N. Mézailles, C. Sanchez, Chem. Rev. 2013, 113, 7981

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 have highlighted the ability of metal surfaces and nanoparticles to undergo restructuring after exposure to CO under fairly mild conditions, generating nanostructures. This Minireview deals with such nanostructuring, and discusses the driving force in reversible and non-reversible situations.

S. Carenco, Chem. Eur. J . 2014, 20, 10616

Electron microscopy is a central tool in materials sciences and nanochemistry. Combining tomography with electron energy loss spectroscopy and high-magnification imaging in high-angle annular dark-field mode provides access to all features of the same object.

In this feature article, we teamed up with colleagues from Strasbourg, CEA Le Ripault, Toulouse and Paris to illustrate a few contributions of electron microscopy techniques in the field of nanomaterials: silica fibers, porous metal oxides, MOFs and metal phosphide nanoparticles.

S. Carenco, S. Moldovan, L. Roiban, I. Florea, D. Portehault, K. Vallé, P. Belleville, C. Boissière, L. Rozes, N. Mézailles, M. Drillon, C. Sanchez, O. Ersen Nanoscale 2016, 8, 1260

This critical review deals with the question of nanoscale phase diagram. Because of their high surface-to-volume ratio, nanoparticles sometimes show phase preferences for certain composition, or even display phase segregation phenomena that one would not expect at the bulk scale. Here, we took metal phosphides as a case study to discuss this exiting side of nanoscale matter.

S. Carenco, D. Portehault, C. Boissière, N. Mézailles, C. Sanchez, Adv. Mater. 2014, 26, 371