R. Kötz

Paul Scherrer Institute

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Alexander Wokaun

Paul Scherrer Institute

Annette Foelske

TU Wien

Otto Haas

Sungkyunkwan University

B. Schnyder

Paul Scherrer Institute

César A. Barbero

National University of Río Cuarto

D. Weingarth

Leibniz-Institute for New Materials

Thomas J. Schmidt

Paul Scherrer Institute

Patrick Ruch

IBM Research - Zurich

Petr Novák

Paul Scherrer Institute

D. Cericola

Imerys (Switzerland)

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Paul Scherrer Institute

109

ETH Zurich

École Polytechnique Fédérale de Lausanne

Centre National de la Recherche Scientifique

Vifor Pharma (Switzerland)

University of Bern

Fritz Haber Institute of the Max Planck Society

Technical University of Munich

Board of the Swiss Federal Institutes of Technology

TU Dresden

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Electrochemical Flow-Cell Setup for In Situ X-ray Investigations

Journal of The Electrochemical Society (2016)

Tobias Binninger Emiliana Fabbri Alexandra Pătru Marios Garganourakis Jun Han

An electrochemical three-electrode flow-cell is presented for in situ small-angle X-ray scattering (SAXS) and X-ray absorption spectroscopy (XAS) experiments in transmission mode at synchrotron X-ray sources. The cell also allows for in situ XAS performed in fluorescence mode. Constant experimental conditions, even under moderate gas evolution, are provided by the electrolyte flow with controlled gas saturation. A special configuration of working and counter electrode, respectively, yields low residual ohmic resistance in three-electrode measurements that enables the study of thick porous electrodes of active high surface area materials. The cell proved its functionality and reliability in two studies: First, an in situ anomalous SAXS experiment for the high-potential degradation properties of a Pt/IrO2-TiO2 catalyst for the oxygen reduction reaction at polymer electrolyte fuel cell cathodes; and second, an in situ XAS study of the electronic state of Ir centers inside an IrO2-TiO2 catalyst under oxygen evolution conditions.

X-ray absorption spectroscopy

Electrochemical cell

10.1149/2.0201610jes

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Citations (102)

Nanoparticles in Energy Technology: Examples from Electrochemistry and Catalysis

Angewandte Chemie International Edition (2005)

Fabio Raimondi Günther G. Scherer R. Kötz Alexander Wokaun

Nanoparticles are key components in the advancement of future energy technologies, thus, strategies for preparing nanoparticles in large volume by techniques that are cost-effective are required. In the substitution of fossil-fuels by renewable energy resources, nanometer-sized particles play a key role for synthesizing energy vectors from varying and heterogeneous biomass feedstocks. They are extensively used in reformers for the production of hydrogen from solid, liquid, or gaseous energy carriers. Catalyst activities depend critically on their size-dependent properties. Nanoparticles are further indispensable as electrocatalysts in fuel cells and other electrochemical converters. The desire to increase the activity per unit area, and decrease the necessary amount of the expensive catalytic standard, platinum, has spurred innovative approaches for the synthesis of platinum-alloy nanoparticles by wet chemistry, colloidal routes, or physical techniques such as sputtering.

Platinum nanoparticles

Electrochemical energy conversion

10.1002/anie.200460466

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Citations (367)

Photochemical Modification of Cross-Linked Poly(dimethylsiloxane) by Irradiation at 172 nm

Macromolecules (2004)

Vera‐Maria Graubner Rainer Jordan Oskar Nuyken B. Schnyder Thomas Lippert

Cross-linked poly(dimethylsiloxane) (PDMS) was irradiated with a Xe2*-excimer lamp (172 nm) under ambient conditions. The irradiation in combination with the formed ozone results in an oxidation of PDMS to SiO2 at the polymer−air interface. The surface properties of the irradiated surfaces were studied by means of contact angle measurements, infrared spectroscopy, and X-ray photoelectron spectroscopy. The photochemical conversion of surface methylsilane groups to silanol groups is responsible for the large increase in surface free energy. Subsequent degradation of the polymer and formation of SiOx was monitored by infrared spectroscopy. As determined by X-ray photoelectron spectroscopy, the binding energy shifts reach values corresponding to SiO2. The atomic ratio concentration O:Si changes from about 1:1 (PDMS) to about 2:1 (SiO2). On the basis of the XPS and IR results, the photochemical reaction pathway from PDMS to silicon oxide via surface silanol groups is discussed. The strict linearity of the contact angle versus irradiation time and the clear dependence from irradiation intensity allows the tuning of the chemical surface functionalities.

Silanol

10.1021/ma049747q

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Citations (146)

Electrochemical doping of single-walled carbon nanotubes in double layer capacitors studied by in situ Raman spectroscopy

Carbon (2008)

Patrick Ruch Laurence J. Hardwick Matthias Hahn Annette Foelske R. Kötz

D band

10.1016/j.carbon.2008.08.023

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Citations (64)

An in situ Raman study of the intercalation of supercapacitor-type electrolyte into microcrystalline graphite

Electrochimica Acta (2006)

Laurence J. Hardwick Matthias Hahn Patrick Ruch Michael Holzapfel Werner Scheifele

Microcrystalline

Pseudocapacitor

10.1016/j.electacta.2006.05.053

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Citations (136)

In-situ XRD and dilatometry investigation of the formation of pillared graphene via electrochemical activation of partially reduced graphite oxide

Electrochimica Acta (2014)

Moritz M. Hantel Reinhard Nesper Alexander Wokaun R. Kötz

Graphite oxide

10.1016/j.electacta.2014.04.063

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Citations (43)

XPS Analysis of Electrochemical Processes at the Ionic Liquid/Electrode and the Ionic Liquid/Ultra High Vacuum Interface

Meeting abstracts/Meeting abstracts (Electrochemical Society. CD-ROM) (2011)

Annette Foelske D. Weingarth Alexander Wokaun R. Kötz

Abstract not Available.

Interface (matter)

10.1149/ma2011-02/44/2547

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A Dilatometric Study of Lithium Intercalation into Powder-Type Graphite Electrodes

Electrochemical and Solid-State Letters (2008)

Matthias Hahn Hilmi Buqa Patrick Ruch Dietrich Goers Michael E. Spahr

The thickness change of porous multiparticle graphite electrodes upon first electrochemical lithium intercalation and extraction was investigated by means of electrochemical dilatometry. For all investigated graphites, expansion starts well above 0.5 V vs and thus, before any unsolvated Li intercalation compounds are formed. This finding can be explained by solvent co intercalation during the first charge prior to SEI formation, as described by the Besenhard model. At potentials vs , i.e., in the region of unsolvated intercalation, the dilatation curves reveal the same major staging features that are seen in the corresponding potential profiles.

10.1149/1.2940573

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Citations (105)

Catalyzed SnO₂ Thin Films: Theoretical and Experimental Insights into Fabrication and Electrocatalytic Properties

The Journal of Physical Chemistry C (2014)

Annett Rabis Denis Kramer Emiliana Fabbri Matthew Worsdale R. Kötz

SnO2 thin films are studied experimentally and from first-principles as model supports for Pt nanoparticle catalysts in an acidic environment. SnO2 thin film supports are attractive model systems because composition, microstructure, and surface termination can be tailored by varying the deposition parameters. SnO2 films are synthesized by reactive dc magnetron sputtering, and the effects of the deposition conditions on the physicochemical and electrochemical properties are investigated experimentally and theoretically. Variation of the deposition conditions results in limited long-range order SnO or SnO2 films. Annealing in either case leads to well-crystallized SnO2 films, but with different growth directions. Films deposited as SnO2 show only growth along the [110] direction, while SnO2 films formed from deposited SnO show no preferred orientations. Hybrid density functional theory (DFT) suggests that growth along the [110] direction is driven by (110) being the lowest energy surface, while the loss of orientation in the SnO derived films originates from an almost degenerate set of surface energies at the SnO|SnO2 equilibrium. The oxygen reduction reaction activity of Pt nanoparticles depends on the SnO2 film orientation. A 2-fold higher catalytic activity is observed for Pt nanoparticles on the SnO2 film without preferential orientation compared to Pt on SnO2 grown along the [110] direction, pointing to the presence of strong surface-dependent metal–support interaction.

Deposition

10.1021/jp4120139

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Citations (34)

Electrochemical characterization of single-walled carbon nanotubes for electrochemical double layer capacitors using non-aqueous electrolyte

Electrochimica Acta (2009)

Patrick Ruch R. Kötz Alexander Wokaun

Gravimetric analysis

10.1016/j.electacta.2009.03.022

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Citations (79)