The Experts below are selected from a list of 3111 Experts worldwide ranked by ideXlab platform
Markus Antonietti - One of the best experts on this subject based on the ideXlab platform.
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Poly(ionic liquid) nanoparticles as novel colloidal template for silica Nanocasting
Polymer, 2014Co-Authors: Sebastian Soll, Markus Antonietti, Jiayin YuanAbstract:Abstract Spherical poly(ionic liquid) (PIL) nanoparticles of different size (25–70 nm) were synthesized and applied as a novel colloidal soft template for the preparation of meso- and macroporous inorganics, here exemplified with silica and its metal nanoparticle doping via Nanocasting. Pore size and pore architecture can be adjusted by appropriate choice of the template and the reaction conditions. Unexpectedly, it was found that the in situ generated methanol plays a very important role during the casting process. It enlarged the overall surface area by introducing a significant fraction of micropores and small mesopores. The largest specific surface area was obtained at an optimized ratio of tetramethyl orthosilicate (TMOS) to PIL nanoparticle. In addition, PIL nanoparticles pre-functionalized with Pt metal nanoparticles were used in the same manner as hybrid templates for Nanocasting. The pyrolysis conditions were optimized to synthesize mesoporous silica functionalized with uniformly distributed metal nanoparticles of very small size in a one-pot process.
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mesoporous g c3n4 nanorods as multifunctional supports of ultrafine metal nanoparticles hydrogen generation from water and reduction of nitrophenol with tandem catalysis in one step
Chemical Science, 2012Co-Authors: Xinchen Wang, Markus AntoniettiAbstract:Flexible mesoporous g-C3N4 nanorods with open channels, synthesized via Nanocasting, can act as catalyst support, solid stabilizer and photosensitizer simultaneously for anchoring uniform metal nanoparticles with high compatibility with the composition, the synthetic method and the particle size. The final hybrid nanorods exhibit high stability and catalytic/photocatalytic activity.
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silica Nanocasting of simple cellulose derivatives towards chiral pore systems with long range order and chiral optical coatings
Advanced Functional Materials, 2003Co-Authors: Arne Thomas, Markus AntoniettiAbstract:Aqueous solutions of hydroxypropyl cellulose with cholesteric superstructures were employed as templates in a silica Nanocasting process, and the resulting pore structures were characterized by polarization microscopy, circular dichroism, X-ray scattering, transmission electron microscopy, and sorption measurements. Whereas the local pore architecture corresponds to a cast of single cellulose strands and their statistical aggregates, the averaged structure on larger scales keeps the cholesteric character, with the cholesteric pitch just slightly shortened.
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porous materials via Nanocasting procedures innovative materials and learning about soft matter organization
Chemical Communications, 2002Co-Authors: Sebastian Polarz, Markus AntoniettiAbstract:Nanocasting, the 3D-transformation of self-assembled organic nanostructures into hollow inorganic replicas under preservation of fine structural details has recently turned out to be a versatile tool, both for the synthesis of porous media with new pore topology as well as for the characterization of the assembled structures themselves. This review gives a review on recent work describing the potential and restrictions of Nanocasting using surfactants, polymers, colloids as well as supramolecular tectons as porogens.
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Preparation of Porous Silica Materials via Sol-Gel Nanocasting of Nonionic Surfactants : A Mechanistic Study on the Self-Aggregation of Amphiphiles for the Precise Prediction of the Mesopore Size
The Journal of Physical Chemistry B, 2001Co-Authors: Bernd M. Smarsly, Sebastian Polarz, Markus AntoniettiAbstract:Sol−gel Nanocasting is used to imprint the soft-matter structures of lyotropic phases of nonionic n-alkyl−poly(ethylene oxide) amphiphiles (“CxEy”) into solid porous silica. Small angle X-ray scattering (SAXS), nitrogen sorption, and transmission electron microscopy (TEM) are used to investigate the dependence of the porosity on the block lengths or the block volumes, respectively. It is found that the size of the mesopores is a function of the lengths/volumes of both the alkyl chain (NA) and the PEO block (NB). Moreover, the materials contain a substantial degree of additional microporosity. A quantitative model is developed that relates the amphiphile organization during the Nanocasting to the size of the mesopores and the microporosity. In particular, it turns out that depending on the number of EO units a fraction of the PEO chains contributes to the mesoporosity, while a significant portion leads to additional micropores. This model provides a quantitative description of the distribution of the hydro...
R.k.c. De Lima - One of the best experts on this subject based on the ideXlab platform.
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high specific surface area lafeco perovskites synthesis by Nanocasting and catalytic behavior in the reduction of no with co
Applied Catalysis B-environmental, 2009Co-Authors: R.k.c. De Lima, Marcelo S. Batista, Martin Wallau, Edgar A. Sanches, Yvonne Primerano Mascarenhas, Ernesto A UrquietagonzalezAbstract:Abstract LaFe 1− x Co x O 3 perovskites were conventionally or Nanocasting synthesized. The Nanocasting involved the preparation of a micro-mesoporous carbon mould using a Silica Aerosil 200 and a carbon source. Then, perovskites were carbon cast at 800 °C. The solids were characterized by XRD, N 2 sorption, FTIR, TGA/DTG, SEM and TEM. N 2 sorption evidenced that the nanocast perovskites did not show significant intraparticle porosity in despite of their enhanced (30–50 m 2 /g) specific surface area (SSA). Nevertheless, TEM images, XRD and Rietveld refinement data showed that the solids are constituted at least by 97 wt% of perovskite phase and by agglomerates smaller than 100 nm constituted by crystallites of about 6 nm. TGA/DTG results demonstrated carbon oxidation during the perovskite formation, thus eliminating the template effect and facilitating the occurrence of sintering, which limited the SSA increase. The nanocast perovskites were more active in the reduction of NO than the uncast ones, behavior that was attributed to the increase in their SSA that allows the exposure of a higher number of accessible active sites. However, the perovskite composition and the presence of impurities can reduce the effect of the improvement of the textural properties. The nanocast perovskites also showed high thermal and catalytic stability, corroborating their potential as catalysts for the studied reaction.
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High specific surface area LaFeCo perovskites—Synthesis by Nanocasting and catalytic behavior in the reduction of NO with CO
Applied Catalysis B-environmental, 2009Co-Authors: R.k.c. De Lima, Marcelo S. Batista, Martin Wallau, Edgar A. Sanches, Yvonne Primerano Mascarenhas, Ernesto A. Urquieta-gonzálezAbstract:Abstract LaFe 1− x Co x O 3 perovskites were conventionally or Nanocasting synthesized. The Nanocasting involved the preparation of a micro-mesoporous carbon mould using a Silica Aerosil 200 and a carbon source. Then, perovskites were carbon cast at 800 °C. The solids were characterized by XRD, N 2 sorption, FTIR, TGA/DTG, SEM and TEM. N 2 sorption evidenced that the nanocast perovskites did not show significant intraparticle porosity in despite of their enhanced (30–50 m 2 /g) specific surface area (SSA). Nevertheless, TEM images, XRD and Rietveld refinement data showed that the solids are constituted at least by 97 wt% of perovskite phase and by agglomerates smaller than 100 nm constituted by crystallites of about 6 nm. TGA/DTG results demonstrated carbon oxidation during the perovskite formation, thus eliminating the template effect and facilitating the occurrence of sintering, which limited the SSA increase. The nanocast perovskites were more active in the reduction of NO than the uncast ones, behavior that was attributed to the increase in their SSA that allows the exposure of a higher number of accessible active sites. However, the perovskite composition and the presence of impurities can reduce the effect of the improvement of the textural properties. The nanocast perovskites also showed high thermal and catalytic stability, corroborating their potential as catalysts for the studied reaction.
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High specific surface area LaFeCo perovskites—Synthesis by Nanocasting and catalytic behavior in the reduction of NO with CO
Applied Catalysis B: Environmental, 2009Co-Authors: R.k.c. De Lima, Marcelo S. Batista, Martin Wallau, Edgar A. Sanches, Yvonne Primerano Mascarenhas, Ernesto A. Urquieta-gonzálezAbstract:LaFe(1-x)CO(x)O(3) perovskites were conventionally or Nanocasting synthesized. The Nanocasting involved the preparation of a micro-mesoporous carbon mould using a Silica Aerosil 200 and a carbon source. Then, perovskites were carbon cast at 800 degrees C. The solids were characterized by XRD, N(2) sorption, FTIR, TGA/DTG, SEM and TEM. N(2) sorption evidenced that the nanocast perovskites did not show significant intraparticle porosity in despite of their enhanced (30-50 m(2)/g) specific surface area (SSA). Nevertheless, TEM images, XRD and Rietveld refinement data showed that the solids are constituted at least by 97 wt% of perovskite phase and by agglomerates smaller than 100 nm constituted by crystallites of about 6 nm. TGA/DTG results demonstrated carbon oxidation during the perovskite formation, thus eliminating the template effect and facilitating the occurrence of sintering, which limited the SSA increase. The nanocast perovskites were more active in the reduction of NO than the uncast ones, behavior that was attributed to the increase in their SSA that allows the exposure of a higher number of accessible active sites. However, the perovskite composition and the presence of impurities can reduce the effect of the improvement of the textural properties. The nanocast perovskites also showed high thermal and catalytic stability, corroborating their potential as catalysts for the studied reaction. (C) 2009 Elsevier B.V. All rights reserved.CNPq/Brazil[505157/2004-7]Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq
Ernesto A. Urquieta-gonzález - One of the best experts on this subject based on the ideXlab platform.
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High specific surface area LaFeCo perovskites—Synthesis by Nanocasting and catalytic behavior in the reduction of NO with CO
Applied Catalysis B-environmental, 2009Co-Authors: R.k.c. De Lima, Marcelo S. Batista, Martin Wallau, Edgar A. Sanches, Yvonne Primerano Mascarenhas, Ernesto A. Urquieta-gonzálezAbstract:Abstract LaFe 1− x Co x O 3 perovskites were conventionally or Nanocasting synthesized. The Nanocasting involved the preparation of a micro-mesoporous carbon mould using a Silica Aerosil 200 and a carbon source. Then, perovskites were carbon cast at 800 °C. The solids were characterized by XRD, N 2 sorption, FTIR, TGA/DTG, SEM and TEM. N 2 sorption evidenced that the nanocast perovskites did not show significant intraparticle porosity in despite of their enhanced (30–50 m 2 /g) specific surface area (SSA). Nevertheless, TEM images, XRD and Rietveld refinement data showed that the solids are constituted at least by 97 wt% of perovskite phase and by agglomerates smaller than 100 nm constituted by crystallites of about 6 nm. TGA/DTG results demonstrated carbon oxidation during the perovskite formation, thus eliminating the template effect and facilitating the occurrence of sintering, which limited the SSA increase. The nanocast perovskites were more active in the reduction of NO than the uncast ones, behavior that was attributed to the increase in their SSA that allows the exposure of a higher number of accessible active sites. However, the perovskite composition and the presence of impurities can reduce the effect of the improvement of the textural properties. The nanocast perovskites also showed high thermal and catalytic stability, corroborating their potential as catalysts for the studied reaction.
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High specific surface area LaFeCo perovskites—Synthesis by Nanocasting and catalytic behavior in the reduction of NO with CO
Applied Catalysis B: Environmental, 2009Co-Authors: R.k.c. De Lima, Marcelo S. Batista, Martin Wallau, Edgar A. Sanches, Yvonne Primerano Mascarenhas, Ernesto A. Urquieta-gonzálezAbstract:LaFe(1-x)CO(x)O(3) perovskites were conventionally or Nanocasting synthesized. The Nanocasting involved the preparation of a micro-mesoporous carbon mould using a Silica Aerosil 200 and a carbon source. Then, perovskites were carbon cast at 800 degrees C. The solids were characterized by XRD, N(2) sorption, FTIR, TGA/DTG, SEM and TEM. N(2) sorption evidenced that the nanocast perovskites did not show significant intraparticle porosity in despite of their enhanced (30-50 m(2)/g) specific surface area (SSA). Nevertheless, TEM images, XRD and Rietveld refinement data showed that the solids are constituted at least by 97 wt% of perovskite phase and by agglomerates smaller than 100 nm constituted by crystallites of about 6 nm. TGA/DTG results demonstrated carbon oxidation during the perovskite formation, thus eliminating the template effect and facilitating the occurrence of sintering, which limited the SSA increase. The nanocast perovskites were more active in the reduction of NO than the uncast ones, behavior that was attributed to the increase in their SSA that allows the exposure of a higher number of accessible active sites. However, the perovskite composition and the presence of impurities can reduce the effect of the improvement of the textural properties. The nanocast perovskites also showed high thermal and catalytic stability, corroborating their potential as catalysts for the studied reaction. (C) 2009 Elsevier B.V. All rights reserved.CNPq/Brazil[505157/2004-7]Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq
Ferdi Schuth - One of the best experts on this subject based on the ideXlab platform.
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Nanocasting design and spatially selective sulfonation of polystyrene based polymer networks as solid acid catalysts
Chemistry: A European Journal, 2016Co-Authors: Laila Sahraoui, Felix H Richter, Ferdi SchuthAbstract:Nanocasting is a general and widely applied method in the generation of porous materials during which a sacrificial solid template is used as a mold on the nanoscale. Ideally, the resulting structure is the inverse of the template. However, replication is not always as direct as anticipated, so the influences of the degree of pore filling and of potential restructuring processes after removal of the template need to be considered. These apparent limitations give rise to opportunities in the synthesis of poly(styrene-co-divinylbenzene) (PSD) polymer networks of widely varying porosities (BET surface area=63-562 m(2) g(-1) ; Vtot =0.18-1.05 cm(3) g(-1) ) by applying a single synthesis methodology. In addition, spatially selective sulfonation on the nanoscale seems possible. Together, Nanocasting and sulfonation enable rational catalyst design. The highly porous nanocast and predominantly surface-sulfonated PSD networks approach the activity of the corresponding molecular catalyst, para-toluenesulfonic acid, and exceed those of commercial ion-exchange polymers in the depolymerization of macromolecular inulin.
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ordered mesoporous co3o4 as highly active catalyst for low temperature co oxidation
Chemical Communications, 2008Co-Authors: Harun Tüysüz, Massimiliano Comotti, Ferdi SchuthAbstract:Cubic ordered mesoporous Co3O4, prepared via the Nanocasting pathway using KIT-6 as hard template, was found to be an excellent catalyst for low temperature CO oxidation, with the activity clearly depending on surface area and pore systems of the catalysts.
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molecular level dispersed pd clusters in the carbon walls of ordered mesoporous carbon as a highly selective alcohol oxidation catalyst
Chemical Communications, 2007Co-Authors: An Hui Lu, Wencui Li, Ferdi SchuthAbstract:Ordered mesoporous carbon containing molecular-level dispersed Pd clusters in the carbon walls can be synthesized by the Nanocasting pathway, which shows high selectivity for the oxidation of alcohols to aldehydes.
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Nanocast mesoporous MgAl2O4 spinel monoliths as support for highly active gold CO oxidation catalyst.
Chemical communications (Cambridge England), 2006Co-Authors: Massimiliano Comotti, Ferdi SchuthAbstract:Mesoporous MgAl2O4 spinel monolith was synthesized by the Nanocasting pathway; high activity in CO oxidation was observed over gold catalysts based on such monoliths as support.
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Nanocasting: A versatile strategy for creating nanostructured porous materials
Advanced Materials, 2006Co-Authors: An Hui Lu, Ferdi SchuthAbstract:Nanocasting is a powerful method for creating materials that are more difficult to synthesize by conventional processes. We summarize recent developments in the synthesis of various structured porous solids, covering silica, carbon, and other nonsiliceous solids that are created by a Nanocasting pathway. Structure replication on the nanometer length scale allows materials' properties to be manipulated in a controlled manner, such as tunable composition, controllable structure and morphology, and specific functionality. The Nanocasting pathway with hard templates opens the door to the design of highly porous solids with multifunctional properties and interesting application perspectives.
Philipp Adelhelm - One of the best experts on this subject based on the ideXlab platform.
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direct synthesis of carbide derived carbon monoliths with hierarchical pore design by hard templating
Journal of Materials Chemistry, 2014Co-Authors: Winfried Nickel, Philipp Adelhelm, M. Von Der Lehr, Bernd M. Smarsly, Martin Oschatz, Matthias Leistner, Guangping Hao, Philipp Muller, Stefan KaskelAbstract:Carbide-derived carbon Monoliths (CDC-Ms) containing a multimodal arrangement with high volumes of micro- meso- and macropores are prepared by direct Nanocasting of silica monoliths with polycarbosilane precursors. CDC-Ms show well-defined pore structures along with specific surface areas of more than 2600 m2 g−1 and overall pore volumes as high as 3.14 cm3 g−1. They exhibit advanced gas filtration properties compared to purely microporous materials due to enhanced storage capacities and kinetics as demonstrated by thermal response measurements based on InfraSORP technology.
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On the use of mesophase pitch for the preparation of hierarchical porous carbon monoliths by Nanocasting
Science and Technology of Advanced Materials, 2012Co-Authors: Philipp Adelhelm, Karin Cabrera, Bernd M. SmarslyAbstract:A detailed study is given on the synthesis of a hierarchical porous carbon, possessing both meso- and macropores, using a mesophase pitch (MP) as the carbon precursor. This carbon material is prepared by the Nanocasting approach involving the replication of a porous silica monolith (hard templating). While this carbon material has already been tested in energy storage applications, various detailed aspects of its formation and structure are addressed in this study. Scanning electron microscopy (SEM), Hg porosimetry and N2 physisorption are used to characterize the morphology and porosity of the carbon replica. A novel approach for the detailed analysis of wide-angle x-ray scattering (WAXS) from non-graphitic carbons is applied to quantitatively compare the graphene microstructures of carbons prepared using MP and furfuryl alcohol (FA). This WAXS analysis underlines the importance of the carbon precursor in the synthesis of templated porous carbon materials via the Nanocasting route. Our study demonstrates that a mesophase pitch is a superior precursor whenever a high-purity, low-micropore-content and well-developed graphene structure is desired.
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room temperature sodium ion batteries improving the rate capability of carbon anode materials by templating strategies
Energy and Environmental Science, 2011Co-Authors: Sebastian Wenzel, Takeshi Hara, Jurgen Janek, Philipp AdelhelmAbstract:Current kinetic limitations of carbon anode materials in sodium-ion batteries can be effectively tackled by using tailor-made carbon materials with hierarchical porosity prepared via the Nanocasting route. Capacities exceeding 100 mA h g−1 at C/5 are found while exhibiting excellent rate capability and reasonable cycle life.
