Synthesis and electrical characterization of monocrystalline nickel nanorods and Ni-CNT composites

Aerospace vessels require electrically conductive, light weight frames to minimize damage from electromagnetic radiation, electrostatic discharge and lightning strikes while economizing fuel. Nickel nanowires and hybrid nickel-carbon nanotube materials are suitable nanostructures to ensure high conductivity at low mass loading. Monocrystalline nickel structures have even better conduction properties than the polycrystalline equivalent due to possessing less particle-particle junctions. We have developed a solutionbased method that produces monocrystalline nickel nanowires via the decomposition of metalorganic precursors in the presence of self-assembled surfactants. The resulting wires are approximately 20 nm wide by 1.5 µm in length. These wires have a morphology consisting of semi-flattened rods with pyramidal ends. Despite the changing dimensions between the nanorod body and its head, there was no disruption in the crystallographic orientation, as observed with HRTEM and diffraction patterns. The nickel nanostructures were exposed to air for several weeks, but no oxidation was detectable by magnetic measurement, i.e. the saturation magnetization corresponds to Ni0 and no bias is observed in the hysteresis loops. It seems that the long alkyl chain amine surfactant, in addition to being a structuration agent, remains at the surface of the Ni wires after washing and acts as a protective layer. The magnetic field around Ni nanowires was imaged using electron holography. Each Ni wire is a magnetic monodomain. Routes to prepare hybrid nickel-CNT materials were explored using chemical vapor deposition in a fluidized bed, solution chemistry and dry preparation in a Fisher-Porter reactor. Different nickel compositions and material morphologies resulted, depending on the preparation technique. The nickel nanorods and hybrid materials were incorporated into carbon fiber-reinforced polymer composites. The electrical conductivity as a function of wt% loading was measured, showing promise for these materials in discharging electrostatic charges

Magnetically induced CO2 methanation using exchange‐coupled spinel ferrites in cuboctahedron‐shaped nanocrystals

Magnetically induced catalysis can be promoted taking advantage of optimal heating properties from the magnetic nanoparticles to be employed. However, when unprotected, these heating agents that are usually air-sensitive, get sintered under the harsh catalytic conditions. In this context, we present, to the best of our knowledge, the first example of air-stable magnetic nanoparticles that: 1) show excellent performance as heating agents in the CO2 methanation catalyzed by Ni/SiRAlOx, with CH4 yields above 95 %, and 2) do not sinter under reaction conditions. To attain both characteristics we demonstrate, first the exchange-coupled magnetic approach as an alternative and effective way to tune the magnetic response and heating efficiency, and second, the chemical stability of cuboctahedron-shaped core–shell hard CoFe2O4–soft Fe3O4 nanoparticles.Xunta de Galicia | Ref. IN607 A 2018/5Xunta de Galicia | Ref. ED431C 2016-034Agencia Estatal de Investigación | Ref. CTM2017-84050-

Ultrastable Magnetic Nanoparticles Encapsulated in Carbon for Magnetically Induced Catalysis

[EN] Magnetically induced catalysis using magnetic nanoparticles (MagNPs) as heating agents is a new efficient method to perform reactions at high temperatures. However, the main limitation is the lack of stability of the catalysts operating in such harsh conditions. Normally, above 500 degrees C, significant sintering of MagNPs takes place. Here we present encapsulated magnetic FeCo and Co NPs in carbon (Co@C and FeCo@C) as an ultrastable heating material suitable for high-temperature magnetic catalysis. Indeed, FeCo@C or a mixture of FeCo@C:Co@C (2:1) decorated with Ni or Pt-Sn showed good stability in terms of temperature and catalytic performances. In addition, consistent conversions and selectivities regarding conventional heating were observed for CO2 methanation (Sabatier reaction), propane dehydrogenation (PDH), and propane dry reforming (PDR). Thus, the encapsulation of MagNPs in carbon constitutes a major advance in the development of stable catalysts for high-temperature magnetically induced catalysis.The authors thank the Instituto de Tecnologia Quimica (ITQ), Consejo Superior de Investigaciones Cientificas (CSIC), Universitat Politecnica de València (UPV) for the facilities and Severo Ochoa programe (SEV-2016-0683), "Juan de la Cierva" by MINECO (IJCI-2016-27966), and Primero Proyectos de Investigación PAID-06-18 (SP20180088) for financial support. The authors acknowledge ERC Advanced Grants (MONACAT-2015-694159 and SynCatMatch-2014671093). We also thank the Electron Microscopy Service of the UPV for TEM facilities.Martínez-Prieto, LM.; Marbaix, J.; Asensio, JM.; Cerezo-Navarrete, C.; Fazzini, P.; Soulantica, K.; Chaudret, B.... (2020). Ultrastable Magnetic Nanoparticles Encapsulated in Carbon for Magnetically Induced Catalysis. ACS Applied Nano Materials. 3(7):7076-7087. https://doi.org/10.1021/acsanm.0c01392S7076708737Ceylan, S., Friese, C., Lammel, C., Mazac, K., & Kirschning, A. (2008). Inductive Heating for Organic Synthesis by Using Functionalized Magnetic Nanoparticles Inside Microreactors. Angewandte Chemie International Edition, 47(46), 8950-8953. doi:10.1002/anie.200801474Ceylan, S., Coutable, L., Wegner, J., & Kirschning, A. (2011). Inductive Heating with Magnetic Materials inside Flow Reactors. Chemistry - A European Journal, 17(6), 1884-1893. doi:10.1002/chem.201002291Houlding, T. K., Gao, P., Degirmenci, V., Tchabanenko, K., & Rebrov, E. V. (2015). Mechanochemical synthesis of TiO2/NiFe2O4 magnetic catalysts for operation under RF field. Materials Science and Engineering: B, 193, 175-180. doi:10.1016/j.mseb.2014.12.011Asensio, J. M., Miguel, A. B., Fazzini, P., van Leeuwen, P. W. N. M., & Chaudret, B. (2019). Hydrodeoxygenation Using Magnetic Induction: High‐Temperature Heterogeneous Catalysis in Solution. Angewandte Chemie International Edition, 58(33), 11306-11310. doi:10.1002/anie.201904366Liu, Y., Gao, P., Cherkasov, N., & Rebrov, E. V. (2016). Direct amide synthesis over core–shell TiO2@NiFe2O4 catalysts in a continuous flow radiofrequency-heated reactor. RSC Advances, 6(103), 100997-101007. doi:10.1039/c6ra22659kLiu, Y., Cherkasov, N., Gao, P., Fernández, J., Lees, M. R., & Rebrov, E. V. (2017). The enhancement of direct amide synthesis reaction rate over TiO 2 @SiO 2 @NiFe 2 O 4 magnetic catalysts in the continuous flow under radiofrequency heating. Journal of Catalysis, 355, 120-130. doi:10.1016/j.jcat.2017.09.010Meffre, A., Mehdaoui, B., Connord, V., Carrey, J., Fazzini, P. F., Lachaize, S., … Chaudret, B. (2015). Complex Nano-objects Displaying Both Magnetic and Catalytic Properties: A Proof of Concept for Magnetically Induced Heterogeneous Catalysis. 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Generation of subnanometric platinum with high stability during transformation of a 2D zeolite into 3D. Nature Materials, 16(1), 132-138. doi:10.1038/nmat4757Liu, L., Zakharov, D. N., Arenal, R., Concepcion, P., Stach, E. A., & Corma, A. (2018). Evolution and stabilization of subnanometric metal species in confined space by in situ TEM. Nature Communications, 9(1). doi:10.1038/s41467-018-03012-6Liu, L., Gao, F., Concepción, P., & Corma, A. (2017). A new strategy to transform mono and bimetallic non-noble metal nanoparticles into highly active and chemoselective hydrogenation catalysts. Journal of Catalysis, 350, 218-225. doi:10.1016/j.jcat.2017.03.014Liu, L., Concepción, P., & Corma, A. (2016). Non-noble metal catalysts for hydrogenation: A facile method for preparing Co nanoparticles covered with thin layered carbon. Journal of Catalysis, 340, 1-9. doi:10.1016/j.jcat.2016.04.006Fu, T., Wang, M., Cai, W., Cui, Y., Gao, F., Peng, L., … Ding, W. (2014). Acid-Resistant Catalysis without Use of Noble Metals: Carbon Nitride with Underlying Nickel. ACS Catalysis, 4(8), 2536-2543. doi:10.1021/cs500523kGarnero, C., Lepesant, M., Garcia-Marcelot, C., Shin, Y., Meny, C., Farger, P., … Chaudret, B. (2019). Chemical Ordering in Bimetallic FeCo Nanoparticles: From a Direct Chemical Synthesis to Application As Efficient High-Frequency Magnetic Material. Nano Letters, 19(2), 1379-1386. doi:10.1021/acs.nanolett.8b05083Lepesant, M., Bardet, B., Lacroix, L.-M., Fau, P., Garnero, C., Chaudret, B., … Gautier, G. (2018). Impregnation of High-Magnetization FeCo Nanoparticles in Mesoporous Silicon: An Experimental Approach. Frontiers in Chemistry, 6. doi:10.3389/fchem.2018.00609Deng, J., Ren, P., Deng, D., & Bao, X. (2015). Enhanced Electron Penetration through an Ultrathin Graphene Layer for Highly Efficient Catalysis of the Hydrogen Evolution Reaction. Angewandte Chemie International Edition, 54(7), 2100-2104. doi:10.1002/anie.201409524Ferrari, A. C. (2007). Raman spectroscopy of graphene and graphite: Disorder, electron–phonon coupling, doping and nonadiabatic effects. Solid State Communications, 143(1-2), 47-57. doi:10.1016/j.ssc.2007.03.052Hadjiev, V. G., Iliev, M. N., & Vergilov, I. V. (1988). The Raman spectra of Co3O4. Journal of Physics C: Solid State Physics, 21(7), L199-L201. doi:10.1088/0022-3719/21/7/007Saxena, P., & Varshney, D. (2017). Effect of d-block element substitution on structural and dielectric properties on iron cobaltite. Journal of Alloys and Compounds, 705, 320-326. doi:10.1016/j.jallcom.2017.02.120Biesinger, M. C., Payne, B. P., Grosvenor, A. P., Lau, L. W. M., Gerson, A. R., & Smart, R. S. C. (2011). Resolving surface chemical states in XPS analysis of first row transition metals, oxides and hydroxides: Cr, Mn, Fe, Co and Ni. Applied Surface Science, 257(7), 2717-2730. doi:10.1016/j.apsusc.2010.10.051Cullity, B. D., & Graham, C. D. (2008). 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Lattice-Confined Sn (IV/II) Stabilizing Raft-Like Pt Clusters: High Selectivity and Durability in Propane Dehydrogenation. ACS Catalysis, 7(10), 6973-6978. doi:10.1021/acscatal.7b02264Hauser, A. W., Gomes, J., Bajdich, M., Head-Gordon, M., & Bell, A. T. (2013). Subnanometer-sized Pt/Sn alloy cluster catalysts for the dehydrogenation of linear alkanes. Physical Chemistry Chemical Physics, 15(47), 20727. doi:10.1039/c3cp53796jBursavich, J., Abu-Laban, M., Muley, P. D., Boldor, D., & Hayes, D. J. (2019). Thermal performance and surface analysis of steel-supported platinum nanoparticles designed for bio-oil catalytic upconversion during radio frequency-based inductive heating. Energy Conversion and Management, 183, 689-697. doi:10.1016/j.enconman.2019.01.025Pashchenko, D. (2017). Thermodynamic equilibrium analysis of combined dry and steam reforming of propane for thermochemical waste-heat recuperation. 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Bidimensional lamellar assembly by coordination of peptidic homopolymers to platinum nanoparticles

A key challenge for designing hybrid materials is the development of chemical tools to control the organization of inorganic nanoobjects at low scales, from mesoscopic (~µm) to nanometric (~nm). So far, the most efficient strategy to align assemblies of nanoparticles consists in a bottom-up approach by decorating block copolymer lamellae with nanoobjects. This well accomplished procedure is nonetheless limited by the thermodynamic constraints that govern copolymer assembly, the entropy of mixing as described by the Flory–Huggins solution theory supplemented by the critical influence of the volume fraction of the block components. Here we show that a completely different approach can lead to tunable 2D lamellar organization of nanoparticles with homopolymers only, on condition that few elementary rules are respected: 1) the polymer spontaneously allows a structural preorganization, 2) the polymer owns functional groups that interact with the nanoparticle surface, 3) the nanoparticles show a surface accessible for coordination

Synergism of Au and Ru Nanoparticles in Low-Temperature Photoassisted CO2 Methanation

This is the peer reviewed version of the following article:Mateo-Mateo, Diego, De Masi, Deborah , Albero-Sancho, Josep, Lacroix, Lisa-Marie , Fazzini, Pier-Francesco , Chaudret, Bruno , García Gómez, Hermenegildo. (2018). Synergism of Au and Ru Nanoparticles in Low-Temperature Photoassisted CO2 Methanation.Chemistry - A European Journal, 24, 69, 18436-18443. DOI: 10.1002/chem.201803022, which has been published in final form at http://doi.org/10.1002/chem.201803022. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions[EN] Au and Ru nanoparticles have been deposited on Siralox® substrate by impregnation and chemical reduction, respectively (Au-Ru-S). The as-prepared material has demonstrated to be very active for the selective CO2 metanation to CH4 at temperatures below 250 oC. In addition, Au-Ru-S exhibits CH4 production enhancement upon UV-Vis light irradiation starting at temepratures higher than 200 oC, although the contribution of the photoassisted pathway of CH4 production decreases as temperature increases. Thus, a maximum CH4 production of 204 mmol/gRu at 250 oC upon 100 mW/cm2 irradiation was achieved. Control experiments using Ru-S and Au-S materials revealed that Ru nanoparticles are the CO2 methanation active sites, while Au NPs contribute harvesting light, mainly visible as consequence of the strong Au plasmon band centrered at 529 nm. The visible light absorbed by Au NPs plasmon could act as local heaters of neighbouring Ru NPs, increasing their temperature and enhancing CH4 production.D. M., J.A., and H.G. thank the Spanish Ministry of Economy and Competitiveness (Severo Ochoa SEV2016-0683 and CTQ2015-69563-CO2-1), Generalitat Valenciana (Prometeo 2017-083) for financial support. J.A. and D.M. also thank UPV for a postdoctoral scholarship and the Spanish Ministry of Science for a PhD Scholarship, respectively. This project has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (grant agreement No GA694159 MONACAT).Mateo-Mateo, D.; De Masi, D.; Albero-Sancho, J.; Lacroix, L.; Fazzini, P.; Chaudret, B.; García Gómez, H. (2018). Synergism of Au and Ru Nanoparticles in Low-Temperature Photoassisted CO2 Methanation. Chemistry - A European Journal. 24(69):18436-18443. https://doi.org/10.1002/chem.201803022S1843618443246

An Improved STEM/EDX Quantitative Method for Dopant Profiling at the Nanoscale

International audienceIn this paper, an improved quantification technique for STEM/EDX measurements of 1D dopant profiles based on the Cliff-Lorimer equation is presented. The technique uses an iterative absorption correction procedure based on density models correlating the local mass density and composition of the specimen. Moreover, a calibration and error estimation procedure based on linear regression and error propagation is proposed in order to estimate the total measurement error in the dopant density. The proposed approach is applied to the measurement of the As profile in a nanodevice test structure. For the calibration, two crystalline Si specimens implanted with different As doses have been used, and the calibration of the Cliff-Lorimer coefficients has been carried out using Rutherford Back Scattering measurements. The As profile measurement has been carried out on an FinFET test structure, showing that quantitative results can be obtained in the nanometer scale and for dopant atomic densities lower than 1%. Using the proposed approach, the measurement error and detection limit for our experimental setup are calculated and the possibility to improve this limit by increasing the observation time is discussed

How to modulate catalytic properties in nanosystems: The case of iron-ruthenium nanoparticles

cited By 7International audienceUltrasmall FeRu bimetallic nanoparticles were prepared by co-decomposition of two organometallic precursors, Fe[N(Si(CH3)3) 2]22 and (η4-1,5- cyclooctadiene)(η6-1,3,5-cyclooctatriene)ruthenium(0) (Ru(COD)(COT)), under dihydrogen at 150 °C in mesitylene. A series of FeRu nanoparticles of sizes of approximately 1.8 nm and incorporating different ratios of iron to ruthenium were synthesized by varying the quantity of the ruthenium complex introduced (Fe/Ru=1:1, 1:0.5, 1:0.2, and 1:0.1). FeRu nanoparticles were characterized by TEM, high-resolution TEM, and wide-angle X-ray scattering analyses. Their surface was studied by hydride titration and IR spectroscopy after CO adsorption and their magnetic properties were analyzed by using a superconducting quantum interference device (SQUID). The FeRu nanoparticles were used as catalysts in the hydrogenation of styrene and 2-butanone. The results indicate that the selectivity of the nanoparticle catalysts can be modulated according to their composition and therefore represent a case study on fine-tuning the reactivity of nanocatalysts and adjusting their selectivity in a given reaction. Singing a bimetallic tune: The selectivity of FeRu nanocatalysts in hydrogenation reactions can be tuned by adjusting the Ru content in bimetallic FeRu ultrasmall nanoparticles

Hydrodeoxygenation and hydrogenolysis of biomass-based materials using FeNi catalysts and magnetic induction

International audienceMagnetically induced catalysis in solution for the valorization of biomass-derived compounds using FeNi 3 @Ni nanoparticles

Extended defects and precipitation in heavily B-doped silicon

International audienceThe boron precipitation phenomenon in highly supersaturated boron-implanted silicon (10 keV B + , 5×10 15 ions/cm 2) has been investigated by means of atom probe tomography, transmission electron microscopy and secondary ion mass spectrometry. We demonstrate that (001) dislocation loops observed by transmission electron microscopy in the region close to the boron projected range and boron precipitates ((001)-platelets) observed by atom probe are the same objects. For sufficiently high thermal budgets (900 °C for 5 h), boron precipitates close to the stoichiometric SiB 3 composition have been observed, indicating that the precipitation induced by high-dose boron implantation can lead to the formation of a stable phase