Bernd Tesche’s research while affiliated with University of Stuttgart and other places

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Publications (135)


ChemInform Abstract: Propene Polymerization with Silica-Supported Metallocene/MAO Catalysts
  • Article

July 2010

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15 Reads

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1 Citation

ChemInform

Gerhard Fink

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Bernd Steinmetz

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Joachim Zechlin

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[...]

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Bernd Tesche

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.


Supported palladium nanoparticles on hybrid mesoporous silica: Structure/activity-relationship in the aerobic alcohol oxidation using supercritical carbon dioxide

September 2008

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38 Reads

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66 Citations

Journal of Catalysis

The preparation, characterization, and catalytic properties of Pd nanoparticles supported on mesoporous organic-inorganic hybrid materials are described for continuous-flow aerobic oxidation of alcohols using supercritical carbon dioxide (scCO(2)) as a mobile phase. The nanoparticles were generated "bottom-up" from molecular precursors that were precoordinated to the support through suitable anchor units. The most active material allows high single-pass conversions in scCO(2) at temperatures as low as 60 degrees C. This high activity may be associated with the presence of small primary crystallites (approx. 2 nm) that conglomerate to ensembles about 25 nm in size, leading to a larger number of high-indexed planes in small volume units. These findings may provide useful guidelines for further catalyst design on the nanoscale for green oxidation methods.


Direct Imaging of Surface Topology and Pore System of Ordered Mesoporous Silica (MCM-41, SBA-15, and KIT-6) and Nanocast Metal Oxides by High Resolution Scanning Electron Microscopy

September 2008

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692 Reads

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199 Citations

Journal of the American Chemical Society

We report here a detailed study on the surface topology of well-known ordered mesoporous silica (SBA-15, MCM-41, and KIT-6) and a series of nanocast Co 3O 4, Co 3O 4/CoFe 2O 4 composites by high resolution scanning electron microscopy (HR-SEM). Images of the MCM-41 structure were obtained at a resolution of the pore size, as well as a real space image of the gyroid silica surface of KIT-6 for two different aging temperatures, clearly revealing the differences of the aging procedures. By using the low voltage HR-SEM technique with extremely high resolution, we could very clearly show the influence of the template properties on the structure of the nanocast metal oxides.


Chemical and Morphological Consequences of Acidification of Pure, Phosphated, and Phosphonated CaO: Influence of CO2 Adsorption

August 2008

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128 Reads

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16 Citations

Langmuir

In situ Fourier transform infrared (FTIR) spectroscopy was employed to characterize the adsorption behavior (as a function of pressure or time) and surface species of CO2 molecules on pure, phosphated, and phosphonated CaO. Carbonate and bicarbonate species were found to form on the pure oxide, whereas on the phosphated and phosphonated oxide samples the carbonate species were found to substitute favorably some of the OH(-) and PO4(3-) groups thereon exposed, respectively. Before and after carbonation, the test samples were further examined by in situ FTIR spectroscopy of adsorbed pyridine species, scanning electron microscopy, and energy dispersive X-ray spectroscopy. Then they were in situ acidified by exposure to a wet atmosphere of HCl vapor at 673 K for 10 min and re-examined similarly to reveal the influence of CO2 adsorption on the chemical and morphological consequences of acidification. The results obtained show the carbonate substitution of PO4(3-) groups to enhance agglomeration of the otherwise fine, longitudinal material particles into much bulkier ones and to render the otherwise more stable phosphonate groups less stable to acid treatment than the phosphate groups. Moreover, the bulky particle agglomerates of the carbonated test samples were detectably eroded following the acid treatment.


Microscopy and Stereology

April 2008

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7 Reads

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2 Citations

IntroductionMicroscopy and SpectroscopyNew Imaging and Analytical Techniques: Tomography (Stereology)Conclusions and OutlookSymbols and Abbreviations


Thermoresponsive polymer-stabilized silver nanoparticles

April 2008

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55 Reads

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55 Citations

Journal of Colloid and Interface Science

Silver nanoparticles (Ag NPs) stabilized by a thermoresponsive polymer, poly(N-isopropylacrylamide) (PNIPAM), have been synthesized by the reduction of silver ions with NaBH(4) in aqueous solutions. The obtained Ag NPs are very stable at room temperature due to the extended coil conformation of the PNIPAM chain at temperatures below its volume phase transition temperature ( approximately 32 degrees C). At higher temperatures (such as 45 degrees C) above the phase transition of PNIPAM, only minute aggregation between Ag NPs was observed, showing that the collapsed PNIPAM chains still retain the ability to stabilize Ag NPs. The PNIPAM-stabilized Ag NPs were then characterized as a function of the thermal phase transition of PNIPAM by UV-vis spectroscopy, dynamic light scattering, transmission electron microscopy, and cyclic voltammeter. Consistent results were obtained showing that the phase transition of PNIPAM has some effect on the optical properties of Ag NPs. Switchable electrochemical response of the PNIPAM-stabilized Ag NPs triggered by temperature change was observed.




Micelle-Assisted One-Pot Synthesis of Water-Soluble Polyaniline−Gold Composite Particles

January 2007

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49 Reads

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72 Citations

Langmuir

A micelle-based method to synthesize dispersed polyaniline (PANI)-Au composite particles by direct oxidation of aniline using AuCl4- as the oxidant is presented. The obtained composite particles have a core-shell structure, where Au nanoparticles of 20 nm mean diameter are encapsulated by PANI of well-defined tetrahedron shape with 150 nm average edge length. The polaron band of the dispersed PANI-Au composite particles is centered at 745 nm and is rather narrow compared to the broad 835 nm absorption of PANI synthesized by the IUPAC procedure. The surface plasmon absorption of Au nanoparticles normally centered at around 520 nm is absent in the composite particles with oxidized PANI. Our results point to a strong electronic interaction between the encapsulated Au nanoparticles and the shell of oxidized PANI. Films and pellets produced from these composite particles show a twofold higher conductivity than IUPAC PANI.


Influence of phosphonation and phosphation on surface acid-base and morphological properties of CaO as investigated by in situ FTIR spectroscopy and electron microscopy

December 2006

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237 Reads

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88 Citations

Journal of Colloid and Interface Science

Pure, phosphated, and phosphonated CaO samples were prepared and characterized by X-ray powder diffractometry, FTIR spectroscopy, scanning electron microscopy, and energy-dispersive X-ray microprobing. Surface acid-base properties were probed by in situ FTIR spectroscopy of adsorbed CO (at 85 K), CDCl3 (at RT), CO2 (at RT), and methyl butynol decomposition reactions (at 473 K). Results obtained have shown phosphate and, to a larger extent, phosphonate additives to enhance the strength of Lewis acid sites exposed on CaO surfaces, at the expense of the Lewis base site strength. The phosphonation has been found, moreover, to make CaO particles grow in a preferential direction and be less susceptible to rehydration. These findings may establish surface chemical attributes for the application of the methylene bisphosphonate (MBP) class of drugs to hamper acid-induced resorption of bone materials (osteoporosis).


Citations (74)


... 47,48 In light of this, the integration of dual stopbands and beyond into an individual photonic structure has gradually received more and more research attention over the past decade. [49][50][51][52] The construction of multiple stopbands photonic structures not only reported from the theoretical perspective, but can be also realized by using different photonic components from the experimental aspect. 53 The different photonic components can be liquid crystals (LC) with different structural colors, colloidal particles with different diameters or the combination of opal and inverse opal structures. ...

Reference:

Advances in the Construction of Photonic Structures with DualStopbands and Beyond
Inverse Opals with a Skeleton Structure: Photonic Crystals with Two Complete Bandgaps
  • Citing Article
  • October 2002

... Magnetic nanosheets with 5-500 nanometers thickness or diameter are commonly used in engineering such as semiconductors, catalysts consisting of nanoparticles, and optical filters. Owe to their marvelous potential features, many magnetic nanosheets have recently been investigated [18][19][20][21]. Consequently, considering flexomagnetic effect becomes necessary for investigating the magneto-mechanical coupling at the nano-scale. ...

Nanoengineering of a magnetically separable hydrogenation catalyst. Angew. Chem
  • Citing Article
  • January 2004

... In o rd er w o rd s : the bo laam p h ip h iles are d isso lved in m e m b ra n e s in a s tre t ched co n fo rm atio n . T his has, fo r ex am p le, been d e m onstrated by q u a n tita tive 1H -N M R an alysis of the b o laam p h ip h iles h e ad g roup s (30), b y reduction of re dox-active h ead g ro u p s (31), or by ap p lica tio n of the m e tach ro m atic e ffe c t in u n sym m e tric m o n o layers (32). ...

ChemInform Abstract: WATER-SOLUBLE α,Ω-BIS(PARAQUAT) AMPHIPHILES FORM MONOLAYER MEMBRANE VESICLES, MICELLES, AND CRYSTALS BY STEPWISE ANION EXCHANGE OR PHOTOCHEMICAL REDUCTION
  • Citing Article
  • July 1984

Chemischer Informationsdienst

... 4,11 De forma geral, a sílica é formada pela agregação de partículas primárias esféricas de diâmetro de 10-100 nm 25,26 formando partículas finais com diâmetro médio de 10-50 mm, que são usualmente empregadas na polimerização. 27,28 Há relatos na literatura sobre a influência do tamanho das partículas primárias, ou mesmo da sua disposição, para catalisadores tipo Philips, 29 na resistência mecânica do material e, consequentemente, na fragmentação da partícula e atividade do catalisador. Entretanto, o tamanho das partículas primárias não influenciou a massa molar do polímero formado. ...

Metalorganic Catalysts for Synthesis and Polymerization
  • Citing Chapter
  • January 1999

... Magnetic colloids can be also influenced by different parameters associated with the sample preparation or even drying including the particle's concentration in the suspension, the viscosity of the media, vapor pressure, surface tension of the solution, temperature, pressure, and even the substrate that is used to dry particles. All these features may affect the formation of the size and shape of particles leading to the formation of different chain-like structures under the magnetic field (Hilgendorff et al., 2001). ...

Creation of 3-D Crystals from Single Cobalt Nanoparticles in External Magnetic Fields
  • Citing Article
  • Publisher preview available
  • February 2002

... Usually, these NP catalysts are prepared from a metal salt, a reducing agent and a stabilizer. NPs have been widely used for their catalytic properties in organic synthesis, for example, in hydrogenation and C-C coupling reactions [2], and the heterogeneous oxidation of CO [3] on AuNPs. ...

Pt/C Catalysts for the Oxygen Reduction Reaction: Correlation of Carbon Support Morphology and Catalytic Activity

Microscopy and Microanalysis

... The three catalysts formed both olefin and paraffin products and the carbon supported materials gave more olefins. A similar result was found for Os/Al 2 O 3 catalysts in the FTS reaction [45] In summary, the 5% Os@HCS and 10% Os@HCS catalysts gave similar results to those observed for the 10% Os/SiO 2 catalyst (and other reported data in the literature) i.e. poor FTS catalytic behaviour with product selectivity mainly to C 1 and C 2 hydrocarbons. ...

CO hydrogenation with alumina-supported catalysts prepared from [Os(CO)5]
  • Citing Article
  • March 1984

Journal of Catalysis

... Functionalization as a term originates from the field of organic chemistry, where it first denoted the covalent binding of atomic groups at a particular carbon site in an organic molecule [1]. Although introduced to the organic chemistry vocabulary in the 1950s, it would take nearly three decades before this term would first be used to describe the covalent attachment of atomic groups onto inorganic materials [2]. Up to this date, the concept of functionalization of nanoparticles has been increasing in popularity, as it can be deduced from the bibliographic trend shown in Fig. S1. ...

Gold-osmium bimetallic catalysts prepared from molecular bimetallic cluster compounds
  • Citing Article
  • July 1984

Journal of Molecular Catalysis

... 1a, b. According to Han et al., Fink and Knoke [5,8,9], a thin polymer layer is formed on the silica particle surface, the polymer layer creates a diffusion barrier for monomer. As polymerization continues, the buildup of hydraulic forces in the particle porous increases, leading to the fragmentation of the silica support from the particle surface to the interior. ...

ChemInform Abstract: Propene Polymerization with Silica-Supported Metallocene/MAO Catalysts
  • Citing Article
  • July 2010

ChemInform

... In case of added H 2 O 2 , Ti-peroxo species tend to be formed at the solution interface [73][74][75][76]. Ohno et al. [75] through FTIR and X-ray photoelectron spectroscopy (XPS) and Lousada et al. [77] through density functional theory studies have confirmed the formation of such peroxo (11) MnT h + (VB) + water → MnT + proton + ⋅OH [78]. ...

Structural Defects Induced in ETS10 by Postsynthesis Treatment with H2O2 Solution
  • Citing Article
  • October 2006

ChemInform