Percus-Yevick theory for the structural properties of the seven-dimensional hard-sphere fluid

The direct correlation function and the (static) structure factor for a seven-dimensional hard-sphere fluid are considered. Analytical results for these quantities are derived within the Percus-Yevick theoryComment: 3 pages, 2 tables, 1 figure; v2: minor changes; to be published in JC

Regioselective Generation of Single-Site Iridium Atoms and Their Evolution into Stabilized Subnanometric Iridium Clusters in MWW Zeolite

This is the peer reviewed version of the following article: L. Liu, M. Lopez-Haro, D. M. Meira, P. Concepcion, J. J. Calvino, A. Corma, Angew. Chem. Int. Ed. 2020, 59, 15695, which has been published in final form at https://doi.org/10.1002/anie.202005621. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.[EN] Preparation of supported metal catalysts with uniform particle size and coordination environment is a challenging and important topic in materials chemistry and catalysis. In this work, we report the regioselective generation of single-site Ir atoms and their evolution into stabilized subnanometric Ir clusters in MWW zeolite, which are located at the 10MR window connecting the two neighboring 12MR supercages. The size of the subnanometric Ir clusters can be controlled by the post-synthesis treatments and maintain below 1 nm even after being reduced at 650 degrees C, which cannot be readily achieved with samples prepared by conventional impregnation methods. The high structure sensitivity, size-dependence, of catalytic performance in the alkane hydrogenolysis reaction of Ir clusters in the subnanometric regime is evidenced.This work has been supported by the European Union through the European Research Council (grant ERC-AdG-2014-671093, SynCatMatch) and the Spanish government through the "Severo Ochoa Program" (SEV-2016-0683). The authors also thank Microscopy Service of UPV for the TEM and STEM measurements. High-resolution STEM measurements were performed at the DME-UCA node of the ELECMI National Singular Infrastruture, in Cadiz University, with financial support from FEDER/MINECO (MAT2017-87579-R and MAT2016-81118-P). This research used resources of the Advanced Photon Source, an Office of Science User Facility operated for the U.S. Department of Energy (DOE) Office of Science by Argonne National Laboratory, and was supported by the U.S. DOE under Contract No.DE-AC02-06CH11357, and the Canadian Light Source and its funding partners. The financial support from ExxonMobil on this project is also greatly acknowledged.Liu, L.; Lopez-Haro, M.; Meira, DM.; Concepción Heydorn, P.; Calvino, JJ.; Corma Canós, A. (2020). Regioselective Generation of Single-Site Iridium Atoms and Their Evolution into Stabilized Subnanometric Iridium Clusters in MWW Zeolite. Angewandte Chemie International Edition. 59(36):15695-15702. https://doi.org/10.1002/anie.202005621S15695157025936Liu, L., & Corma, A. (2018). Metal Catalysts for Heterogeneous Catalysis: From Single Atoms to Nanoclusters and Nanoparticles. Chemical Reviews, 118(10), 4981-5079. doi:10.1021/acs.chemrev.7b00776Thomas, J. M., Raja, R., & Lewis, D. W. (2005). 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Angewandte Chemie, 131(51), 18743-18749. doi:10.1002/ange.201912367Liu, Y., Li, Z., Yu, Q., Chen, Y., Chai, Z., Zhao, G., … Li, Y. (2019). A General Strategy for Fabricating Isolated Single Metal Atomic Site Catalysts in Y Zeolite. Journal of the American Chemical Society, 141(23), 9305-9311. doi:10.1021/jacs.9b02936Wu, S., Yang, X., & Janiak, C. (2019). Confinement Effects in Zeolite‐Confined Noble Metals. Angewandte Chemie International Edition, 58(36), 12340-12354. doi:10.1002/anie.201900013Wu, S., Yang, X., & Janiak, C. (2019). Confinement Effects in Zeolite‐Confined Noble Metals. Angewandte Chemie, 131(36), 12468-12482. doi:10.1002/ange.201900013Liu, L., Lopez-Haro, M., Lopes, C. W., Li, C., Concepcion, P., Simonelli, L., … Corma, A. (2019). Regioselective generation and reactivity control of subnanometric platinum clusters in zeolites for high-temperature catalysis. Nature Materials, 18(8), 866-873. doi:10.1038/s41563-019-0412-6Camblor, M. A., Corma, A., Díaz-Cabañas, M.-J., & Baerlocher, C. (1998). Synthesis and Structural Characterization of MWW Type Zeolite ITQ-1, the Pure Silica Analog of MCM-22 and SSZ-25. The Journal of Physical Chemistry B, 102(1), 44-51. doi:10.1021/jp972319kYücelen, E., Lazić, I., & Bosch, E. G. T. (2018). Phase contrast scanning transmission electron microscopy imaging of light and heavy atoms at the limit of contrast and resolution. Scientific Reports, 8(1). doi:10.1038/s41598-018-20377-2Liu, L., Wang, N., Zhu, C., Liu, X., Zhu, Y., Guo, P., … Han, Y. (2020). Direct Imaging of Atomically Dispersed Molybdenum that Enables Location of Aluminum in the Framework of Zeolite ZSM‐5. Angewandte Chemie International Edition, 59(2), 819-825. doi:10.1002/anie.201909834Liu, L., Wang, N., Zhu, C., Liu, X., Zhu, Y., Guo, P., … Han, Y. (2019). Direct Imaging of Atomically Dispersed Molybdenum that Enables Location of Aluminum in the Framework of Zeolite ZSM‐5. Angewandte Chemie, 132(2), 829-835. doi:10.1002/ange.201909834Schroeder, C., Mück‐Lichtenfeld, C., Xu, L., Grosso‐Giordano, N. A., Okrut, A., Chen, C., … Koller, H. (2020). A Stable Silanol Triad in the Zeolite Catalyst SSZ‐70. Angewandte Chemie International Edition, 59(27), 10939-10943. doi:10.1002/anie.202001364Schroeder, C., Mück‐Lichtenfeld, C., Xu, L., Grosso‐Giordano, N. A., Okrut, A., Chen, C., … Koller, H. (2020). Stabile Silanoltriaden im Zeolithkatalysator SSZ‐70. Angewandte Chemie, 132(27), 11032-11036. doi:10.1002/ange.202001364Corma, A., Fornes, V., Pergher, S. B., Maesen, T. L. M., & Buglass, J. G. (1998). Delaminated zeolite precursors as selective acidic catalysts. Nature, 396(6709), 353-356. doi:10.1038/24592Leonowicz, M. E., Lawton, J. A., Lawton, S. L., & Rubin, M. K. (1994). MCM-22: A Molecular Sieve with Two Independent Multidimensional Channel Systems. Science, 264(5167), 1910-1913. doi:10.1126/science.264.5167.1910Moliner, M., Gabay, J. E., Kliewer, C. E., Carr, R. T., Guzman, J., Casty, G. L., … Corma, A. (2016). Reversible Transformation of Pt Nanoparticles into Single Atoms inside High-Silica Chabazite Zeolite. Journal of the American Chemical Society, 138(48), 15743-15750. doi:10.1021/jacs.6b10169Liu, 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/s41467-018-03012-6Yan, W., Xi, S., Du, Y., Schreyer, M. K., Tan, S. X., Liu, Y., & Borgna, A. (2018). Heteroatomic Zn-MWW Zeolite Developed for Catalytic Dehydrogenation Reactions: A Combined Experimental and DFT Study. ChemCatChem, 10(14), 3078-3085. doi:10.1002/cctc.201800199De Graaf, J., van Dillen, A. ., de Jong, K. ., & Koningsberger, D. . (2001). Preparation of Highly Dispersed Pt Particles in Zeolite Y with a Narrow Particle Size Distribution: Characterization by Hydrogen Chemisorption, TEM, EXAFS Spectroscopy, and Particle Modeling. Journal of Catalysis, 203(2), 307-321. doi:10.1006/jcat.2001.3337Jentys, A. (1999). Estimation of mean size and shape of small metal particles by EXAFS. Physical Chemistry Chemical Physics, 1(17), 4059-4063. doi:10.1039/a904654bLu, J., Serna, P., Aydin, C., Browning, N. D., & Gates, B. C. (2011). Supported Molecular Iridium Catalysts: Resolving Effects of Metal Nuclearity and Supports as Ligands. Journal of the American Chemical Society, 133(40), 16186-16195. doi:10.1021/ja206486jZhao, A., & Gates, B. C. (1996). Hexairidium Clusters Supported on γ-Al2O3:  Synthesis, Structure, and Catalytic Activity for Toluene Hydrogenation. Journal of the American Chemical Society, 118(10), 2458-2469. doi:10.1021/ja952996xNoei, H., Franz, D., Creutzburg, M., Müller, P., Krausert, K., Grånäs, E., … Stierle, A. (2018). Monitoring the Interaction of CO with Graphene Supported Ir Clusters by Vibrational Spectroscopy and Density Functional Theory Calculations. The Journal of Physical Chemistry C, 122(8), 4281-4289. doi:10.1021/acs.jpcc.7b10845Fielicke, A., Gruene, P., Meijer, G., & Rayner, D. M. (2009). The adsorption of CO on transition metal clusters: A case study of cluster surface chemistry. Surface Science, 603(10-12), 1427-1433. doi:10.1016/j.susc.2008.09.064Henninen, T. R., Bon, M., Wang, F., Passerone, D., & Erni, R. (2020). The Structure of Sub‐nm Platinum Clusters at Elevated Temperatures. Angewandte Chemie International Edition, 59(2), 839-845. doi:10.1002/anie.201911068Henninen, T. R., Bon, M., Wang, F., Passerone, D., & Erni, R. (2019). The Structure of Sub‐nm Platinum Clusters at Elevated Temperatures. Angewandte Chemie, 132(2), 849-855. doi:10.1002/ange.201911068Okumura, M., Irie, Y., Kitagawa, Y., Fujitani, T., Maeda, Y., Kasai, T., & Yamaguchi, K. (2006). DFT studies of interaction of Ir cluster with O2, CO and NO. Catalysis Today, 111(3-4), 311-315. doi:10.1016/j.cattod.2005.10.042Flaherty, D. W., & Iglesia, E. (2013). Transition-State Enthalpy and Entropy Effects on Reactivity and Selectivity in Hydrogenolysis of n-Alkanes. Journal of the American Chemical Society, 135(49), 18586-18599. doi:10.1021/ja4093743Talu, O., Sun, M. S., & Shah, D. B. (1998). Diffusivities ofn-alkanes in silicalite by steady-state single-crystal membrane technique. AIChE Journal, 44(3), 681-694. doi:10.1002/aic.690440316Flaherty, D. W., Uzun, A., & Iglesia, E. (2015). Catalytic Ring Opening of Cycloalkanes on Ir Clusters: Alkyl Substitution Effects on the Structure and Stability of C–C Bond Cleavage Transition States. The Journal of Physical Chemistry C, 119(5), 2597-2613. doi:10.1021/jp511688xHibbitts, D. D., Flaherty, D. W., & Iglesia, E. (2015). Role of Branching on the Rate and Mechanism of C–C Cleavage in Alkanes on Metal Surfaces. 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Journal of Catalysis, 297, 70-78. doi:10.1016/j.jcat.2012.09.01

Key insights on the structural characterization of textured Er2O3–ZrO2 nano-oxides prepared by a surfactant-free solvothermal route

Zirconia-mixed oxides can exhibit cubic fluorite and pyrochlore structure. Their discrimination is not easy in nanooxides with a crystal size close to that of a few unit cells. In this work, high resolution transmission electron microscopy (HRTEM) has been employed to provide key insights on the structural characterization of a nanometric and porous mixed Er2O3–ZrO2 oxide. The material was prepared by a simple template-free solvothermal route that provided nanocrystalline powders at low temperature (170 °C) with spherical morphology, and high surface area (∼280 m2 g−1). The porosity was mainly originated from the assembling of organic complexing agents used in the synthesis to limit the crystal growth and to control hydrolysis and condensation reaction rates. The samples were characterized by thermal analysis, X-ray diffraction, scanning electron microscopy and N2 adsorption measurements. A detailed study by HRTEM was conducted on microtomed samples. It was observed that the material was made of nanocrystals packed into spherical agglomerates. HRTEM simulations indicated that it is not possible to identify the pyrochlore phase in nanoparticles with diameter below 2 nm. In our samples, the analysis of the HRTEM lattice images by means of fast Fourier transform (FFT) techniques revealed well defined spots that can be assigned to different planes of a cubic fluorite-type phase, even in the raw material. Raman spectroscopy was also a powerful technique to elucidate the crystalline phase of the materials with the smallest nanoparticles. HREM and Raman results evidenced that the material is constituted, irrespective of the temperature of the final calcination step, by an ensemble of randomly oriented nanocrystals with fluorite structure. This study opens new perspectives for the design of synthetic approaches to prepare nanooxides (fluorites and pyrochlores) and the analysis of their crystalline structure

Regioselective generation and reactivity control of subnanometric platinum clusters in zeolites for high-temperature catalysis

[EN] Subnanometric metal species (single atoms and clusters) have been demonstrated to be unique compared with their nanoparticulate counterparts. However, the poor stabilization of subnanometric metal species towards sintering at high temperature (>500 degrees C) under oxidative or reductive reaction conditions limits their catalytic application. Zeolites can serve as an ideal support to stabilize subnanometric metal catalysts, but it is challenging to localize subnanometric metal species on specific sites and modulate their reactivity. We have achieved a very high preference for localization of highly stable subnanometric Pt and PtSn clusters in the sinusoidal channels of purely siliceous MFI zeolite, as revealed by atomically resolved electron microscopy combining high-angle annular dark-field and integrated differential phase contrast imaging techniques. These catalysts show very high stability, selectivity and activity for the industrially important dehydrogenation of propane to form propylene. This stabilization strategy could be extended to other crystalline porous materials.This work has been supported by the European Union through the European Research Council (grant ERC-AdG-2014-671093, SynCatMatch) and the Spanish government through the Severo Ochoa Programme (SEV-2016-0683). L.L. thanks ITQ for providing a contract. The authors also thank the Microscopy Service of UPV for the TEM and STEM measurements. The XAS measurements were carried out in CLAESS beamline at the ALBA synchrotron. HR STEM measurements were performed at DME-UCA in Cadiz University with financial support from FEDER/MINECO (MAT2017-87579-R and MAT2016-81118-P). A relevant patent application (European patent application No. 19382024.8) has been presented. C.W.L. thanks CAPES (Science without Frontiers-Process no. 13191/13-6) for a predoctoral fellowship.Liu, L.; Lopez-Haro, M.; Lopes, CW.; Li, C.; Concepción Heydorn, P.; Simonelli, L.; Calvino, JJ.... (2019). Regioselective generation and reactivity control of subnanometric platinum clusters in zeolites for high-temperature catalysis. Nature Materials. 18(8):866-875. https://doi.org/10.1038/s41563-019-0412-6S86687518

Composition Analysis of III-Nitrides at the Nanometer Scale: Comparison of Energy Dispersive X-ray Spectroscopy and Atom Probe Tomography

International audienc

Gradual transformation of Ag2S to Au2S nanoparticles by sequential cation exchange reactions: binary, ternary, and hybrid compositions

Cation exchange reactions have been exploited in the last years as an efficient tool for the controlled chemical modi-fication of pre-made nanocrystals. In this work, the gradual transformation of Ag2S nanocrystals into Au2S analogues is performed by sequential cation exchange reactions that allow for a fine control of the chemical composition, delivering also two intermediate ternary sulfides based exclusively on noble metals. The role of two different surfactants in the reaction medium has been studied: while dodecylamine is favoring the heterogeneous nucleation of metallic Au on the surface of the semiconductor domains in detri-ment of the cation exchange reaction, the use of tetraoctylammonium bromide turns out to be crucial for the enhancement of the exchange in order to reach full cation substitution, if desired. The presence of Br- anions in the reaction medium represents an additional tool to modulate the morphology of the final nanocrystals, being either solid or hollow depending on their concentration. The synthetic protocol has been successfully conducted in both spherical and rod-like nanocrystals with identical results, leading to a wide variety of binary, ternary and/or hybrid nanostructures that have been carefully characterized

Active and Regioselective Ru Single-Site Heterogeneous Catalystsfor Alpha-Olefin Hydroformylation

[EN] A heterogeneous ruthenium catalyst consisting ofisolated single atoms and disordered clusters stabilized in a N-doped carbon matrix has been synthesized with very good activityand remarkable regioselectivity in the hydroformylation of 1-hexene. The role of the nitrogen heteroatoms has been probedessential to increase the catalyst stability and activity, enabling thestabilization of Ru(II)-N sites according to X-ray photoelectronspectroscopy (XPS) and XANES. Intrinsic size-dependent activityof Ru species of different atomicity has been extracted, correlatingthe observed reaction rate and the particle size distributiondetermined by means of aberration-corrected high-angle annulardark-field scanning transmission electron microscopy, permittingthe identification of single-atom sites as the most active ones. This catalyst appears as a promising alternative with respect to itsheterogeneous counterparts, paving the way for designing improved Ru heterogeneous catalysts.The research leading to these results has received funding from the Spanish Ministry of Science, Innovation and Universities, through the "Severo Ochoa" Excellence Programme (SEV2016-0683) and RTI2018-099668-B-C21 and PGC2018101247-B-100 "Programa Estatal de Generacion de Conocimiento". P.C acknowledges the financial support from the "Generalitat Valenciana" through the project AICO/2020/205. HR-HAADF-STEM measurements were performed at the DME-UCA node of ELECMI ICTS with financial support from FEDER/MINECO (MAT2017-87579-R and PID2019110018GA-I00); XAS experiments were performed at the BL22-CLAESS beamline at the ALBA Synchrotron with the collaboration of ALBA staff as part of projects 2019093692 and 2020024106. XPS experiments were performed at the BL24CIRCE beamline at the ALBA Synchrotron with the collaboration of ALBA staff. J.E.B acknowledges the Polytechnical University of Valencia for the economic support through the grant of an FPI scholarship associated with the PAID programme "Programa de Ayudas de Investigacion y Desarrollo".Escobar-Bedia, FJ.; Lopez-Haro, M.; Calvino, JJ.; Martin-Diaconescu, V.; Simonelli, L.; Pérez-Dieste, V.; Sabater Picot, MJ.... (2022). Active and Regioselective Ru Single-Site Heterogeneous Catalystsfor Alpha-Olefin Hydroformylation. ACS Catalysis. 12(7):4182-4193. https://doi.org/10.1021/acscatal.1c057374182419312

Soluble/MOF-Supported Palladium Single Atoms Catalyze the Ligand-, Additive-, and Solvent-Free Aerobic Oxidation of Benzyl Alcohols to Benzoic Acids

Metal single-atom catalysts (SACs) promise great rewards in terms of metal atom efficiency. However, the requirement of particular conditions and supports for their synthesis, together with the need of solvents and additives for catalytic implementation, often precludes their use under industrially viable conditions. Here, we show that palladium single atoms are spontaneously formed after dissolving tiny amounts of palladium salts in neat benzyl alcohols, to catalyze their direct aerobic oxidation to benzoic acids without ligands, additives, or solvents. With this result in hand, the gram-scale preparation and stabilization of Pd SACs within the functional channels of a novel methyl-cysteine-based metal-organic framework (MOF) was accomplished, to give a robust and crystalline solid catalyst fully characterized with the help of single-crystal X-ray diffraction (SCXRD). These results illustrate the advantages of metal speciation in ligand-free homogeneous organic reactions and the translation into solid catalysts for potential industrial implementation.This work was supported by the Ministero dell’Istruzione, dell’Università e della Ricerca (Italy) and the MINECO (Spain) (Projects PID2019−104778GB−I00, CTQ 2017–86735–P, RTC–2017–6331–5, Severo Ochoa program SEV–2016–0683 and Excellence Unit “Maria de Maeztu” CEX2019−000919−M). E.T. and M.M. thank MINECO and ITQ for the concession of a contract. D.A. acknowledges the financial support of the Fondazione CARIPLO/“Economia Circolare: ricerca per un futuro sostenibile” 2019, Project code: 2019–2090, MOCA and Diamond Light Source for awarded beamtime and provision of synchrotron radiation facilities and thanks Dr. Sarah Barnett and David Allan for their assistance at I19 beamline (Proposal No. MT18768-1). Thanks are also extended to the “2019 Post-doctoral Junior Leader-Retaining Fellowship, la Caixa Foundation (ID100010434 and fellowship code LCF/BQ/PR19/11700011” (J.F.-S.) and “La Caixa” scholarship (ID 100010434) LCF/BQ/DI19/11730029 (J.B.-S). E.P. acknowledges the financial support of the European Research Council under the European Union’s Horizon 2020 research and innovation programme/ERC Grant Agreement No 814804, MOF reactors. J.O.-M. acknowledges the Juan de la Cierva program for the concession of a contract (IJC2018-036514-I). We gratefully acknowledge to ALBA synchrotron for allocating beamtime and CLÆSS beamline staff for their technical support during our experiment. The computations were performed on the Tirant III cluster of the Servei d’Informàtica of the University of Valencia.Peer reviewe

Regioirregular and catalytic Mizoroki-Heck reactions

[EN] The palladium-catalysed cross-coupling reaction between alkenes and aryl halides (the Mizoroki-Heck reaction) is a powerful methodology to construct new carbon-carbon bonds. However, the success of this reaction is in part hampered by an extremely marked regioselectivity on the double bond, which dictates that electron-poor alkenes react exclusively on the beta-carbon. Here, we show that ligand-free, few-atom palladium clusters in solution catalyse the alpha-selective intramolecular Mizoroki-Heck coupling of iodoaryl cinnamates, and mechanistic studies support the formation of a sterically encumbered cinnamate-palladium cluster intermediate. Following this rationale, the alpha-selective intermolecular coupling of aryl iodides with styrenes is also achieved with palladium clusters encapsulated within fine-tuned and sterically restricted zeolite cavities to produce 1,1-bisarylethylenes, which are further engaged with aryl halides by a metal-free photoredox-catalysed coupling. These ligand-free methodologies significantly expand the chemical space of the Mizoroki-Heck coupling.This work was supported by MINECO (Spain, projects CTQ 2017-86735-P, PID2019-105391GB-C22 and MAT2017-82288-C2-1-P, Severo Ochoa programme SEV-2016-0683 and the Juan de la Cierva programme). F.G.-P. and R.G. thank ITQ for the concession of a contract. J.O.-M. acknowledges the Juan de la Cierva programme for the concession of a contract, and R.P.-R. and J.C.-S. thank the Plan GenT programme (CIDEGENT/2018/044) funded by Generalitat Valenciana. HR STEM measurements were performed at DME-UCA in Cadiz University, with financial support from FEDER/MINECO (PID2019-110018GA-I00 and PID2019-107578GA-I00). We acknowledge ALBA Synchrotron for allocating beamtime and CL AE SS beamline staff for their technical support during our experiment.Garnes-Portoles, F.; Greco, R.; Oliver-Meseguer, J.; Castellanos-Soriano, J.; Jiménez Molero, MC.; Lopez-Haro, M.; Hernández-Garrido, JC.... (2021). Regioirregular and catalytic Mizoroki-Heck reactions. Nature Catalysis. 4(4):293-303. https://doi.org/10.1038/s41929-021-00592-3S2933034

Interplay between gonadal hormones and postnatal overfeeding in defining sex-dependent differences in gut microbiota architecture

Aging is associated with a decline in sex hormones, variable between sexes, that has an impact on many different body systems and might contribute to age-related disease progression. We aimed to characterize the sex differences in gut microbiota; and. to explore the impact of depletion of gonacial hormones, alone or combined with postnatal overfeeding, in rats. Many of the differences in the gut microbiota between sexes persisted after gonadectomy, but removal of gonadal hormones shaped several gut microbiota features towards a more deleterious profile, the effect being greater in females than in males, mainly when animals were concurrently overfed. Moreover, we identified several intestinal miRNAs as potential mediators of the impact of changes in gut microbiota on host organism physiology. Our study points out that gonadal hormones contribute to defining sex-dependent differences of gut microbiota, and discloses a potential role of gonadal hormones in shaping gut microbidta, OS consequence of the interaction between sex and nutrition. Our data suggest that the changes in gut microbion, observed in conditions of sex hormone decline, as those caused by ageing in men and menopause in women, might exert different effects on the host organism, which are putatively mediated by gut microbiota-intestinal miRNA cross-talk