hcp -Co Nanowires grown on metallic foams as catalysts for Fischer-Tropsch Synthesis

The Fischer-Tropsch synthesis (FTS) is a structure‐sensitive exothermic reaction that enables catalytic transformation of syngas to high quality liquid fuels. Now, monolithic cobalt‐based heterogeneous catalysts were elaborated through a wet chemistry approach that allows control over nanocrystal shape and crystallographic phase, while at the same time enables heat management. Copper and nickel foams have been employed as supports for the epitaxial growth of hcp‐Co nanowires directly from a solution containing a coordination compound of cobalt and stabilizing ligands. The Co/Cufoam catalyst was tested for Fischer-Tropsch synthesis in a fixed‐bed reactor, showing stability and significantly superior activity and selectivity towards C5+ compared to a Co/SiO2‐Al2O3 reference catalyst under the same conditions

Direct protein quantification in complex sample solutions by surface-engineered nanorod probes

Detecting biomarkers from complex sample solutions is the key objective of molecular diagnostics. Being able to do so in a simple approach that does not require laborious sample preparation, sophisticated equipment and trained staff is vital for point-of-care applications. Here, we report on the specific detection of the breast cancer biomarker sHER2 directly from serum and saliva samples by a nanorod-based homogeneous biosensing approach, which is easy to operate as it only requires mixing of the samples with the nanorod probes. By careful nanorod surface engineering and homogeneous assay design, we demonstrate that the formation of a protein corona around the nanoparticles does not limit the applicability of our detection method, but on the contrary enables us to conduct in-situ reference measurements, thus further strengthening the point-of-care applicability of our method. Making use of sandwich assays on top of the nanorods, we obtain a limit of detection of 110 pM and 470 pM in 10-fold diluted spiked saliva and serum samples, respectively. In conclusion, our results open up numerous applications in direct protein biomarker quantification, specifically in point-of-care settings where resources are limited and ease-of-use is of essenceThis research was supported by the European Commission FP7 NAMDIATREAM project (EU NMP4-LA-2010–246479), and the German Research Foundation (DFG grant PA 794/25-1)S

CO2 methanation activated by magnetic heating: life cycle assessment and perspectives for successful renewable energy storage

Purpose Technologies with low environmental impacts and promoting renewable energy sources are required to meet the energetic demand while facing the increase of gas emissions associated to the greenhouse effect and the depletion of fossil fuels. CO2 methanation activated by magnetic heating has recently been reported as a highly efficient and innovative power-to-gas technology in a perspective of successful renewable energy storage and carbon dioxide valorisation. In this work, the life cycle assessment (LCA) of this process is performed, in order to highlight the environmental potential of the technology, and its competitivity with in respect to conventional heating technologies. Methods The IMPACT 2002+ was used for this LCA. The process studied integrates methanation, water electrolysis and CO2 capture and separation. This “cradle-to-gate” LCA study does not consider the use of methane, which is the reaction product. The functional unit used is the energy content of the produced CH4. The LCA was carried out using the energy mix data for the years 2020 and 2050 as given by the French Agency for Environment and Energy management (ADEME). Consumption data were either collected from literature or obtained from the LPCNO measurements as discussed by Marbaix (2019). The environmental impact of the CO2 methanation activated by magnetic heating was compared with the environmental impact of a power-to-gas plant using conventional heating (Helmeth) and considering the environmental impact of the natural gas extraction. Results It is shown that the total flow rate of reactants, the source of CO2 and the energy mix play a major role on the environmental impact of sustainable CH4 production, whereas the lifetime of the considered catalyst has no significant influence. As a result of the possible improvements on the above-mentioned parameters, the whole process is expected to reduce by 75% in its environmental impact toward 2050. This illustrates the high environmental potential of the methanation activated by magnetic heating when coupled with industrial exhausts and renewable electricity production. Conclusions The technology is expected to be environmentally competitive compared with existing similar processes using external heating sources with the additional interest of being extremely dynamic in response, in line with the intermittency of renewable energy production

Homogeneous Biosensing Based on Magnetic Particle Labels

The growing availability of biomarker panels for molecular diagnostics is leading to an increasing need for fast and sensitive biosensing technologies that are applicable to point-of-care testing. In that regard, homogeneous measurement principles are especially relevant as they usually do not require extensive sample preparation procedures, thus reducing the total analysis time and maximizing ease-of-use. In this review, we focus on homogeneous biosensors for the in vitro detection of biomarkers. Within this broad range of biosensors, we concentrate on methods that apply magnetic particle labels. The advantage of such methods lies in the added possibility to manipulate the particle labels by applied magnetic fields, which can be exploited, for example, to decrease incubation times or to enhance the signal-to-noise-ratio of the measurement signal by applying frequency-selective detection. In our review, we discriminate the corresponding methods based on the nature of the acquired measurement signal, which can either be based on magnetic or optical detection. The underlying measurement principles of the different techniques are discussed, and biosensing examples for all techniques are reported, thereby demonstrating the broad applicability of homogeneous in vitro biosensing based on magnetic particle label actuation

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. Nano Letters, 15(5), 3241-3248. doi:10.1021/acs.nanolett.5b00446Bordet, A., Lacroix, L.-M., Fazzini, P.-F., Carrey, J., Soulantica, K., & Chaudret, B. (2016). Magnetically Induced Continuous CO2Hydrogenation Using Composite Iron Carbide Nanoparticles of Exceptionally High Heating Power. Angewandte Chemie International Edition, 55(51), 15894-15898. doi:10.1002/anie.201609477Mortensen, P. M., Engbæk, J. S., Vendelbo, S. B., Hansen, M. F., & Østberg, M. (2017). Direct Hysteresis Heating of Catalytically Active Ni–Co Nanoparticles as Steam Reforming Catalyst. Industrial & Engineering Chemistry Research, 56(47), 14006-14013. doi:10.1021/acs.iecr.7b02331Marbaix, J., Mille, N., Lacroix, L.-M., Asensio, J. M., Fazzini, P.-F., Soulantica, K., … Chaudret, B. (2020). Tuning the Composition of FeCo Nanoparticle Heating Agents for Magnetically Induced Catalysis. ACS Applied Nano Materials, 3(4), 3767-3778. doi:10.1021/acsanm.0c00444Vinum, M. G., Almind, M. R., Engbæk, J. S., Vendelbo, S. B., Hansen, M. F., Frandsen, C., … Mortensen, P. M. (2018). Dual‐Function Cobalt–Nickel Nanoparticles Tailored for High‐Temperature Induction‐Heated Steam Methane Reforming. Angewandte Chemie International Edition, 57(33), 10569-10573. doi:10.1002/anie.201804832Kale, S. S., Asensio, J. M., Estrader, M., Werner, M., Bordet, A., Yi, D., … Chaudret, B. (2019). Iron carbide or iron carbide/cobalt nanoparticles for magnetically-induced CO2 hydrogenation over Ni/SiRAlOx catalysts. Catalysis Science & Technology, 9(10), 2601-2607. doi:10.1039/c9cy00437hVarsano, F., Bellusci, M., La Barbera, A., Petrecca, M., Albino, M., & Sangregorio, C. (2019). Dry reforming of methane powered by magnetic induction. International Journal of Hydrogen Energy, 44(38), 21037-21044. doi:10.1016/j.ijhydene.2019.02.055Wang, W., Duong-Viet, C., Xu, Z., Ba, H., Tuci, G., Giambastiani, G., … Pham-Huu, C. (2020). CO2 methanation under dynamic operational mode using nickel nanoparticles decorated carbon felt (Ni/OCF) combined with inductive heating. Catalysis Today, 357, 214-220. doi:10.1016/j.cattod.2019.02.050Benkowsky, G. Induktionserwärmung: Härten, Glühen, Schmelzen, Löten, Schweißn: Grundlagen und praktische Anleitungen für Induktionserwärmungsverfahren, insbesondere auf dem Gebiet der Hochfrequenzerwärmung, 5th ed. Verlag Technik: Berlin, 1990; p 12.Carrey, J., Mehdaoui, B., & Respaud, M. (2011). Simple models for dynamic hysteresis loop calculations of magnetic single-domain nanoparticles: Application to magnetic hyperthermia optimization. Journal of Applied Physics, 109(8), 083921. doi:10.1063/1.3551582Khodakov, A. Y., Chu, W., & Fongarland, P. (2007). Advances in the Development of Novel Cobalt Fischer−Tropsch Catalysts for Synthesis of Long-Chain Hydrocarbons and Clean Fuels. Chemical Reviews, 107(5), 1692-1744. doi:10.1021/cr050972vLiu, J., Guo, Z., Childers, D., Schweitzer, N., Marshall, C. L., Klie, R. F., … Meyer, R. J. (2014). Correlating the degree of metal–promoter interaction to ethanol selectivity over MnRh/CNTs CO hydrogenation catalysts. Journal of Catalysis, 313, 149-158. doi:10.1016/j.jcat.2014.03.002Ghaib, K., Nitz, K., & Ben-Fares, F.-Z. (2016). Chemical Methanation of CO2: A Review. ChemBioEng Reviews, 3(6), 266-275. doi:10.1002/cben.201600022Cored, J., García-Ortiz, A., Iborra, S., Climent, M. J., Liu, L., Chuang, C.-H., … Corma, A. (2019). Hydrothermal Synthesis of Ruthenium Nanoparticles with a Metallic Core and a Ruthenium Carbide Shell for Low-Temperature Activation of CO2 to Methane. Journal of the American Chemical Society, 141(49), 19304-19311. doi:10.1021/jacs.9b07088Schiermeier, Q. (2013). Location may stymie wind and solar power benefits. Nature. doi:10.1038/nature.2013.13258Wilhelm, D. ., Simbeck, D. ., Karp, A. ., & Dickenson, R. . (2001). Syngas production for gas-to-liquids applications: technologies, issues and outlook. Fuel Processing Technology, 71(1-3), 139-148. doi:10.1016/s0378-3820(01)00140-0Sattler, J. J. H. B., Ruiz-Martinez, J., Santillan-Jimenez, E., & Weckhuysen, B. M. (2014). Catalytic Dehydrogenation of Light Alkanes on Metals and Metal Oxides. Chemical Reviews, 114(20), 10613-10653. doi:10.1021/cr5002436Siahvashi, A., Chesterfield, D., & Adesina, A. A. (2013). Propane CO2 (dry) reforming over bimetallic Mo–Ni/Al2O3 catalyst. Chemical Engineering Science, 93, 313-325. doi:10.1016/j.ces.2013.02.003Lee, M.-H., Nagaraja, B. M., Lee, K. Y., & Jung, K.-D. (2014). Dehydrogenation of alkane to light olefin over PtSn/θ-Al2O3 catalyst: Effects of Sn loading. Catalysis Today, 232, 53-62. doi:10.1016/j.cattod.2013.10.011Liu, L., Díaz, U., Arenal, R., Agostini, G., Concepción, P., & Corma, A. (2016). 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). Introduction to Magnetic Materials. doi:10.1002/9780470386323Zhang, Y., Zhu, Y., Wang, K., Li, D., Wang, D., Ding, F., … Zhang, Z. (2018). Controlled synthesis of Co2C nanochains using cobalt laurate as precursor: Structure, growth mechanism and magnetic properties. Journal of Magnetism and Magnetic Materials, 456, 71-77. doi:10.1016/j.jmmm.2018.02.014Desvaux, C., Amiens, C., Fejes, P., Renaud, P., Respaud, M., Lecante, P., … Chaudret, B. (2005). Multimillimetre-large superlattices of air-stable iron–cobalt nanoparticles. Nature Materials, 4(10), 750-753. doi:10.1038/nmat1480Desvaux, C., Dumestre, F., Amiens, C., Respaud, M., Lecante, P., Snoeck, E., … Chaudret, B. (2009). FeCo nanoparticles from an organometallic approach: synthesis, organisation and physical properties. Journal of Materials Chemistry, 19(20), 3268. doi:10.1039/b816509bNogués, J., & Schuller, I. K. (1999). Exchange bias. Journal of Magnetism and Magnetic Materials, 192(2), 203-232. doi:10.1016/s0304-8853(98)00266-2Saville, S. L., Qi, B., Baker, J., Stone, R., Camley, R. E., Livesey, K. L., … Thompson Mefford, O. (2014). The formation of linear aggregates in magnetic hyperthermia: Implications on specific absorption rate and magnetic anisotropy. Journal of Colloid and Interface Science, 424, 141-151. doi:10.1016/j.jcis.2014.03.007Mehdaoui, B., Tan, R. P., Meffre, A., Carrey, J., Lachaize, S., Chaudret, B., & Respaud, M. (2013). Increase of magnetic hyperthermia efficiency due to dipolar interactions in low-anisotropy magnetic nanoparticles: Theoretical and experimental results. Physical Review B, 87(17). doi:10.1103/physrevb.87.174419Mehdaoui, B., Meffre, A., Lacroix, L.-M., Carrey, J., Lachaize, S., Respaud, M., … Chaudret, B. (2010). Magnetic anisotropy determination and magnetic hyperthermia properties of small Fe nanoparticles in the superparamagnetic regime. Journal of Applied Physics, 107(9), 09A324. doi:10.1063/1.3348795Serantes, D., Simeonidis, K., Angelakeris, M., Chubykalo-Fesenko, O., Marciello, M., Morales, M. del P., … Martinez-Boubeta, C. (2014). Multiplying Magnetic Hyperthermia Response by Nanoparticle Assembling. The Journal of Physical Chemistry C, 118(11), 5927-5934. doi:10.1021/jp410717mAsensio, J. M., Marbaix, J., Mille, N., Lacroix, L.-M., Soulantica, K., Fazzini, P.-F., … Chaudret, B. (2019). To heat or not to heat: a study of the performances of iron carbide nanoparticles in magnetic heating. Nanoscale, 11(12), 5402-5411. doi:10.1039/c8nr10235jXiong, H., Lin, S., Goetze, J., Pletcher, P., Guo, H., Kovarik, L., … Datye, A. K. (2017). Thermally Stable and Regenerable Platinum–Tin Clusters for Propane Dehydrogenation Prepared by Atom Trapping on Ceria. Angewandte Chemie International Edition, 56(31), 8986-8991. doi:10.1002/anie.201701115Zhu, Y., An, Z., Song, H., Xiang, X., Yan, W., & He, J. (2017). 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. International Journal of Hydrogen Energy, 42(22), 14926-14935. doi:10.1016/j.ijhydene.2017.04.284Ojeda, M., Nabar, R., Nilekar, A. U., Ishikawa, A., Mavrikakis, M., & Iglesia, E. (2010). CO activation pathways and the mechanism of Fischer–Tropsch synthesis. Journal of Catalysis, 272(2), 287-297. doi:10.1016/j.jcat.2010.04.012Gao, J., Wang, Y., Ping, Y., Hu, D., Xu, G., Gu, F., & Su, F. (2012). A thermodynamic analysis of methanation reactions of carbon oxides for the production of synthetic natural gas. RSC Advances, 2(6), 2358. doi:10.1039/c2ra00632dZangeneh, F. T., Taeb, A., Gholivand, K., & Sahebdelfar, S. (2015). Thermodynamic Equilibrium Analysis of Propane Dehydrogenation with Carbon Dioxide and Side Reactions. Chemical Engineering Communications, 203(4), 557-565. doi:10.1080/00986445.2015.1017638Wang, X., Wang, N., Zhao, J., & Wang, L. (2010). Thermodynamic analysis of propane dry and steam reforming for synthesis gas or hydrogen production. International Journal of Hydrogen Energy, 35(23), 12800-12807. doi:10.1016/j.ijhydene.2010.08.132Martínez-Prieto, L. M., Puche, M., Cerezo-Navarrete, C., & Chaudret, B. (2019). Uniform Ru nanoparticles on N-doped graphene for selective hydrogenation of fatty acids to alcohols. Journal of Catalysis, 377, 429-437. doi:10.1016/j.jcat.2019.07.040Soulantica, K., Maisonnat, A., Fromen, M.-C., Casanove, M.-J., & Chaudret, B. (2003). Spontaneous Formation of Ordered 3D Superlattices of Nanocrystals from Polydisperse Colloidal Solutions. Angewandte Chemie International Edition, 42(17), 1945-1949. doi:10.1002/anie.20025048

A setup to measure the temperature-dependent heating power of magnetically heated nanoparticles up to high temperature.

Magnetic heating, namely, the use of heat released by magnetic nanoparticles (MNPs) excited with a high-frequency magnetic field, has so far been mainly used for biological applications. More recently, it has been shown that this heat can be used to catalyze chemical reactions, some of them occurring at temperatures up to 700 °C. The full exploitation of MNP heating properties requires the knowledge of the temperature dependence of their heating power up to high temperatures. Here, a setup to perform such measurements is described based on the use of a pyrometer for high-temperature measurements and on a protocol based on the acquisition of cooling curves, which allows us to take into account calorimeter losses. We demonstrate that the setup permits to perform measurements under a controlled atmosphere on solid state samples up to 550 °C. It should in principle be able to perform measurements up to 900 °C. The method, uncertainties, and possible artifacts are described and analyzed in detail. The influence on losses of putting under vacuum different parts of the calorimeter is measured. To illustrate the setup possibilities, the temperature dependence of heating power is measured on four samples displaying very different behaviors. Their heating power increases or decreases with temperature, displaying temperature sensibilities ranging from -2.5 to +4.4% K-1. This setup is useful to characterize the MNPs for magnetically heated catalysis applications and to produce data that will be used to test models permitting to predict the temperature dependence of MNP heating power

High temperature structural and magnetic properties of cobalt nanowires

We present in this paper the structural and magnetic properties of high aspect ratio Co nanoparticles (~10) at high temperatures (up to 623 K) using in situ X ray diffraction (XRD) and SQUID characterizations. We show that the anisotropic shapes, the structural and texture properties are preserved up to 500 K. The coercivity can be modelled by u0Hc=2(Kmc+Kshape)/Ms with Kmc the magnetocrystalline anisotropy constant, Kshape the shape anisotropy constant and Ms the saturation magnetization. Hc decreases linearly when the temperature is increased due to the loss of the Co magnetocrystalline anisotropy contribution. At 500K, 50% of the room temperature coercivity is preserved corresponding to the shape anisotropy contribution only. We show that the coercivity drop is reversible in the range 300 - 500 K in good agreement with the absence of particle alteration. Above 525 K, the magnetic properties are irreversibly altered either by sintering or by oxidation.Comment: 8 pages, 7 figures, submitted to Journal of Solid State Chemistr

Chemical Ordering in Bimetallic FeCo Nanoparticles: From a Direct Chemical Synthesis to Application As Efficient High-Frequency Magnetic Material

Single-crystalline FeCo nanoparticles with tunable size and shape were prepared by co-decomposing two metal-amide precursors under mild conditions. The nature of the ligands introduced in this organometallic synthesis drastically affects the reactivity of the precursors and, thus, the chemical distribution within the nanoparticles. The presence of the B2 short-range order was evidenced in FeCo nanoparticles prepared in the presence of HDAHCl ligands, combining 57 Fe Mössbauer, zero-field 59 Co ferromagnetic nuclear resonance (FNR), and X-ray diffraction studies. This is the first time that the B2 structure is directly formed during synthesis without the need of any annealing step. The as-prepared nanoparticles exhibit magnetic properties comparable with the ones for the bulk (M s = 226 Am 2 ·kg -1 ). Composite magnetic materials prepared from these FeCo nanoparticles led to a successful proof-of-concept of the integration on inductor-based filters (27% enhancement of the inductance value at 100 MHz)

Chemical ordering in bimetallic FeCo nanoparticles: From a direct chemical synthesis to application as efficient high-frequency magnetic material

Single-crystalline FeCo nanoparticles with tunable size and shape were prepared by co-decomposing two metal-amide precursors under mild conditions. The nature of the ligands introduced in this organometallic synthesis drastically affects the reactivity of the precursors and, thus, the chemical distribution within the nanoparticles. The presence of the B2 short-range order was evidenced in FeCo nanoparticles prepared in the presence of HDAHCl ligands, combining 57Fe Mössbauer, zero-field 59Co ferromagnetic nuclear resonance (FNR), and X-ray diffraction studies. This is the first time that the B2 structure is directly formed during synthesis without the need of any annealing step. The as-prepared nanoparticles exhibit magnetic properties comparable with the ones for the bulk (Ms = 226 Am2·kg¿1). Composite magnetic materials prepared from these FeCo nanoparticles led to a successful proof-of-concept of the integration on inductor-based filters (27% enhancement of the inductance value at 100 MHz).This work was performed in the frame of TOURS 2015, and the project was supported by the French “Programme de l’économie numérique des Investissements d’Avenir”. We gratefully acknowledge the International Associated Laboratory (LIA)-M2OZART for financial support. Some of the HR-STEM and EELS studies were conducted at the Laboratorio de Microscopias Avanzadas, Instituto de Nanociencia de Aragon, Universidad de Zaragoza, Spain. R.A. gratefully acknowledges the support from the Spanish Ministry of Economy and Competitiveness (MINECO) through project MAT2016-79776-P (AEF/FEDER. UE). In IPCMS Strasbourg, the work was supported by the CNRS LIA “NANOFUNC” and the LABEX NIE (no. ANR-11-LABX-0058_NIE)

Theory as a driving force to understand reactions on nanoparticles: general discussion

International audienc