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Gasparotto L.H.S.,Institute of Particle Technology | Prowald A.,EFZN Goslar | Borisenko N.,Institute of Particle Technology | El Abedin S.Z.,Institute of Particle Technology | And 3 more authors.
Journal of Power Sources | Year: 2011

In the present study macroporous aluminium electrodes were made by template assisted electrodeposition from ionic liquids. Polystyrene (PS) spheres (diameter 600 nm) were applied onto polished copper electrodes by immersion into an alcoholic suspension containing PS spheres. Al was deposited from the chloroaluminate ionic liquid [EMIm]Cl/AlCl3 (40/60 mol.%) on this substrate. After chemical dissolution of the PS spheres a macroporous aluminium electrode was obtained which served as a host material for Li deposition from ionic liquids. Lithium deposition in this matrix is reversible showing certain activation with an increasing number of cycles. After 10 cycles of Li deposition/dissolution the macroporous structure is still visible. © 2010 Elsevier B.V. All rights reserved.

Al Zoubi M.,Institute of Particle Technology | Al-Salman R.,Institute of Particle Technology | El Abedin S.Z.,Institute of Particle Technology | El Abedin S.Z.,National Research Center of Egypt | And 2 more authors.
ChemPhysChem | Year: 2011

The electrochemical synthesis of gallium nanostructures in an ionic liquid is presented. Gallium nanowires and macroporous structures were synthesized by the template-assisted electrodeposition in the ionic liquid 1-butyl-1- methylpyrrolidinium bis(trifluoromethylsulfonyl)amide ([Py1,4]TFSA) containing GaCl3 as the precursor. Track-etched polycarbonate membranes with an average pore diameter of 90 nm and a thickness of 21 μm were used as templates for the nanowire synthesis. Ga nanowires with a length of more than 4 μm and an average diameter corresponding to that of the template's pores were easily obtained by this method. Macroporous structures with an average pore diameter of 600 nm were obtained by the electrochemical deposition of Ga inside polystyrene colloidal crystal templates and the subsequent removal of the template by THF. The macroporous deposit showed a granular morphology with smallest grain sizes of about 40 nm and light reflections. The nanostructures of Ga were characterized by HR-SEM and EDX analysis. Ga get it! The electrochemical synthesis of gallium nanostructures by template-assisted electrodeposition in an ionic liquid is presented. The picture shows photographs of a sample of macroporous Ga (600 nm pore size) displaying different colors due to light reflections upon changing the angle of incident white light. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Prowald A.,EFZN Energieforschungszentrum Goslar | El Abedin S.Z.,Institute of Particle Technology | El Abedin S.Z.,National Research Center of Egypt | Borisenko N.,Institute of Particle Technology | Endres F.,Institute of Particle Technology
Zeitschrift fur Physikalische Chemie | Year: 2012

One challenge in the use of metallic lithium in secondary lithium ion or lithium air batteries is the dendritic growth of lithium upon repeated cycling which might either lead to a short circuit or at least to an uneven current distribution and bad cycling stability. In the present paper we present our first results on the electrodeposition of lithium from an ionic liquid within the voids of a polystyrene opal structure on copper. For this purpose polystyrene spheres with an average diameter of about 600 nm were applied onto a copper sheet by a simple dipping process resulting in a layer thickness of about 10 μm. Lithium can be deposited within this polymer structure without damaging it and the subsequent dissolution of the polystyrene spheres delivers a macroporous lithium film, proving that a mechanically stable composite electrode is feasible. © by Oldenbourg Wissenschaftsverlag, München.

Vassilev V.,Institute of Particle Technology | Groschel M.,Friedrich - Alexander - University, Erlangen - Nuremberg | Schmid H.-J.,University of Paderborn | Peukert W.,Institute of Particle Technology | Leugering G.,Friedrich - Alexander - University, Erlangen - Nuremberg
Chemical Engineering Science | Year: 2010

In this paper, we consider a model for precipitation experiments based on the population balance equation. The study revealed a high sensitivity of the system with respect to the modeling of intrinsic parameters, motivating a comprehensive validation of the estimates. In the forward simulation the impact of the influencing parameters including surface energy, nucleus size and distribution is investigated. Subsequently we construct a simplified model of the precipitation process in such a way that it is orbitally flat in terms of control theory, which enables the inverse calculation of the parameters. The numerical results of the inverse simulation for the interfacial energy have been compared to a physical model. The possibility of solving the inverse problem provides a promising way of estimating hardly measurable quantities for more complex molecules. © 2009 Elsevier Ltd. All rights reserved.

Distaso M.,Institute of Particle Technology | Mackovic M.,Center for Nanoanalysis and Electronic Microscopy | Spiecker E.,Center for Nanoanalysis and Electronic Microscopy | Peukert W.,Institute of Particle Technology
Chemistry - A European Journal | Year: 2014

By using ZnO as a model system, the formation of twinned nanostructures has been investigated under microwave irradiation, exploiting experimental conditions ranging from purely solvothermal when N,N-dimethylformamide was used, to purely hydrothermal when water was the solvent. A progressive increase in size, elongation and roughness of the surface was observed with increasing water content in the solvent mixture. Particular attention was paid to the reactivity of the ZnO surfaces towards dissolution. Our results show that the formation of twinned nanorods is a dynamic process and that the coupling interphase itself is highly reactive. Consequently, the twinned rods undergo a number of complex dissolution processes that are responsible for the appearance of a wide distribution of defects either on the surface or inside the structure. Poly(N-vinyl pyrrolidone) influences the photoluminescent properties of the as-synthesised materials and allows control of the ratio of the intensity of the UV and visible emission. Split at the seam cut! By increasing the water content of N,N-dimethylformamide reaction mixtures, the growth of anisotropic twinned ZnO nanostructures is achieved, characterised by the presence of a seam cut (see figure). Defect formation and surface dissolution occur, especially at the seam cut. The emission from defects is effectively quenched by using poly(vinyl pyrrolidone) during the synthesis. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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