Johanna Heine  Constantin Hoch  Ullrich Jahn  Stefan Knecht  Hajo Kries  Bjrn Meermann  Andreas Schnepf  Carl Christoph Tzschucke  Markus Zegke 《Nachrichten aus der Chemie》2019,67(12):38-41

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Guillaume Delaittre  Johanna Heine  Ullrich Jahn  Stefan Knecht  Hajo Kries  Bjrn Meermann  Andreas Schnepf  Erik Strub  Carl Christoph Tzschucke 《Nachrichten aus der Chemie》2019,67(3):42-45

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Guillaume Delaittre  Johanna Heine  Constantin Hoch  Ullrich Jahn  Stefan Knecht  Hajo Kries  Bjrn Meermann  Andreas Schnepf  Carl Christoph Tzschucke  Markus Zegke 《Nachrichten aus der Chemie》2019,67(7-8):44-47

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Naeem-ul-Hasan Saddiqi  Debabrata Patra  Prof. Stefan Seeger 《Chemphyschem》2019,20(4):538-544

Germanium oxide nanofilaments (GNFs) have been synthesized under ambient conditions from the gas phase using germanium tetrachloride as a precursor. Non-crystalline GNFs synthesized by this procedure are 1–10 μm in length and 80–110 nm in diameter applying Droplet Assisted Growth and Shaping (DAGS) Chemistry. The relative humidity has been adjusted at various values in order to demonstrate the crucial role of humidity in the gas phase for the nanofilament synthesis. The novel GNFs show a strong luminescence emission in the ultra-violet and light blue region. In addition, a self-cleaning and superhydrophobic properties could be introduced in the luminescent GNF nanofilaments by simple treatment with silane molecules.  相似文献   

    

Christina Schneidermann  Christian Kensy  Pascal Otto  Dr. Steffen Oswald  Dr. Lars Giebeler  Desirée Leistenschneider  Sven Grätz  Dr. Susanne Dörfler  Prof. Dr. Stefan Kaskel  Dr. Lars Borchardt 《ChemSusChem》2019,12(1):310-319

Nitrogen-doped carbons were synthesized by a solvent-free mechanochemically induced one-pot synthesis by using renewable biomass waste. Three solid materials are used: sawdust as a carbon source, urea and/or melamine as a nitrogen source, and potassium carbonate as an activation agent. The resulting nitrogen-doped porous carbons offer a very high specific surface area of up to 3000 m² g⁻¹ and a large pore volume up to 2 cm³ g⁻¹. Also, a high nitrogen content of 4 wt % (urea only) up to 12 wt % (melamine only) is generated, depending on the nitrogen and carbon sources. The mechanochemical reaction and the impact of different wood components on the porosity and surface functionalities are investigated by nitrogen physisorption and high-resolution X-ray photoelectron spectroscopy (XPS). These N-doped carbons are highly suitable as cathode materials for Li–S batteries, showing high initial discharge capacities of up to 1300 mAh g_sulfur⁻¹ (95 % coulombic efficiency) and >75 % capacity retention within the first 50 cycles at low electrolyte volume.  相似文献   

    

Denis Öhl  David Franzen  Dr. Melanie Paulisch  Stefan Dieckhöfer  Dr. Stefan Barwe  Prof. Dr. Corina Andronescu  Dr. Ingo Manke  Prof. Dr. Thomas Turek  Prof. Dr. Wolfgang Schuhmann 《ChemSusChem》2019,12(12):2732-2739

Electrocatalytically active materials on the industrial as well as on the laboratory scale may suffer from chemical instability during operation, air exposure, or storage in the electrolyte. A strategy to recover the loss of electrocatalytic activity is presented. Oxygen-depolarized cathodes (ODC), analogous to those that are utilized in industrial brine electrolysis, are analyzed: the catalytic activity of the electrodes upon storage (4 weeks) under industrial process conditions (30 wt % NaOH, without operation) diminishes. This phenomenon occurs as a consequence of surface oxidation and pore blockage, as revealed by scanning electron microscopy, focused ion beam milling, X-ray photoelectron spectroscopy, and Raman spectroscopy. Potentiodynamic cycling of the oxidized electrodes to highly reductive potentials and the formation of “nascent” hydrogen re-reduces the electrode material, ultimately recovering the former catalytic activity.  相似文献   

    

Dr. Majid Vafaeezadeh  Paul Breuninger  Philipp Lösch  Dr. Christian Wilhelm  Prof. Dr. Stefan Ernst  Prof. Dr. Sergiy Antonyuk  Prof. Dr. Werner R. Thiel 《ChemCatChem》2019,11(9):2304-2312

In this work, amphiphilic silica-based Janus-type acid and base catalysts are introduced as heterogeneous analogues of surfactants. The new interphase organic-inorganic hybrid catalysts comprise of two different groups (−C₈H₁₇, −C₂H₄Ph) on the hydrophobic and two different groups (−C₃H₆SO₃H, −C₃H₆NH₂) on the hydrophilic side. The hydrophobic sides of the catalysts are responsible for the diffusion of the organic substrates to the catalytically active sites while the hydrophilic sides carry catalytic centers being oriented towards the aqueous phase and thus providing sufficient connection between water (solvent) and the organic substrates. Catalyst preparation is based on simple synthetic procedures and leads in a first step to hollow silica spheres with hydrophobic groups on the inner and hydrophilic groups on the outer surface. After crushing the hollow spheres, acid resp. base functionalized Janus nano-sheets are obtained. The basic catalyst was tested for the Knoevenagel condensation of a series of benzaldehydes with malononitrile in water, while the acid catalyst was used for Fischer esterification of acetic acid with ethanol.  相似文献   

    

Cornelia Broicher  Feng Zeng  Dr. Jens Artz  Dr. Heinrich Hartmann  Dr. Astrid Besmehn  Dr. Stefan Palkovits  Prof. Dr. Regina Palkovits 《ChemCatChem》2019,11(1):412-416

The development of novel metal oxide catalysts for electrochemical water splitting has been one of the future challenges in catalysis. We present the development of structured spinel based NiCo₂O₄ materials using in-situ hydrothermal synthesis and KIT-6 as a template. Their electron transfer kinetics in the oxygen evolution reaction (OER) at pH 14 are studied. Structuring of NiCo₂O₄ via KIT-6 improves the intrinsic catalyst performance, e. g., a lower overpotential of ∼350 mV and a good long-term stability could be observed compared to 385 mV and poor stability of commercially available NiCo₂O₄. Kinetic studies provided insights into structure-activity relations and the nature of the electrode/electrolyte interface. Interestingly, structuring via KIT-6 increases not only the electrochemical surface area but also the current density accompanied by superior charge transfer capacity.  相似文献   

    

Alexander Brodsky  Natan Kaplan  Stefan Liebl  Rainer Franke 《Laser Technik Journal》2019,16(2):37-41

Laser welding is used in a wide range of industrial applications including automotive, aerospace, semiconductors, electronics, medical, power, defense, and others. The raw laser beam is not the optimal shape for many industrial applications in general and especially in the field of welding, brazing, soldering, and other similar processes. Compared to other laser material processing applications, these processes stand out in terms of the required laser power (multi kW) and the highly multimode beams often used. A process-specific tailored laser intensity distribution can improve throughput, seam height, strength, and the edge smoothness of the joints.  相似文献   

    

Stefan K. Estreicher  Trey M. Vincent  Christopher M. Stanley 《physica status solidi (a)》2019,216(10)

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