Publications de Gunther Wittstock

Effect of TiO2 Photoanodes Morphology and Dye Structure on Dye-Regeneration Kinetics Investigated by Scanning Electrochemical Microscopy

Nikolaos Vlachopoulos, Ulf Anders Hagfeldt, Gunther Wittstock, Kazuteru Nonomura

The dye regeneration in dye-sensitized solar cells (DSSCs) is improved by optimizing the charge separation at the level of the sensitized semiconductor treatment of the mesoporous electrode by TiCl4 that passivates the surface for back electron transfer re ...

2020

Diverging surface reactions at TiO2- or ZnO-based photoanodes in dye-sensitized solar cells

Nikolaos Vlachopoulos, Ulf Anders Hagfeldt, Gunther Wittstock, Kazuteru Nonomura

Fast recombination of electrons from semiconductors with the oxidized redox species in the electrolyte represents a major bottleneck in the improvement of ZnO-based dye-sensitized solar cells (DSSCs). While processes at the semiconductor-electrolyte interf ...

ROYAL SOC CHEMISTRY2019

A Simple Liquid-Liquid Biphasic System for Hydrogen Peroxide Generation

Hubert Girault, Gunther Wittstock

Although electron transfer reactions at liquid liquid interfaces have been thoroughly studied in the presence of deliberately added potential determining ions or phase transfer catalysts, little is known about these reactions in the absence of the above sp ...

American Chemical Society2015

Influence of Dye Architecture of Triphenylamine Based Organic Dyes on the Kinetics in Dye-Sensitized Solar Cells

Ulf Anders Hagfeldt, Gunther Wittstock

The impact of the dye architecture on the kinetics in the dyesensitized solar cell (DSC) was investigated for two structurally similar organic dyes, adsorbed adsorbed to a mesoporous TiO2 film. Differences in the HOMO and LUMO levels of the triphenylamine ...

American Chemical Society2015

Catalysis at room temperature ionic liquid|water interface: H2O2 generation

Hubert Girault, Gunther Wittstock

H2O2 is produced at the interface between a room-temperature ionic liquid with decamethylferrocene as electron donor and an acidic aqueous solution. The electron donor can be regenerated electrochemically. ...

Royal Society of Chemistry2015

Finger Probe Array for Topography-Tolerant Scanning Electrochemical Microscopy of Extended Samples

Hubert Girault, Gunther Wittstock, Fernando Cortes Salazar, Dmitry Momotenko, Andreas Stephan Lesch

Scanning electrochemical microscopy with soft microelectrode array probes has recently been used to enable reactivity imaging of extended areas and to compensate sample corrugation perpendicular to the scanning direction. Here, the use of a new type of mic ...

Amer Chemical Soc2014

High-throughput scanning electrochemical microscopy brushing of strongly tilted and curved surfaces

Hubert Girault, Gunther Wittstock, Fernando Cortes Salazar, Dmitry Momotenko, Andreas Stephan Lesch

The feasibility of high-throughput scanning electrochemical microscopy (SECM) of strongly tilted (tilt angles ≤4°) and curved substrates (diameter of curvature ≥9 cm) is demonstrated by brushing them with a soft linear array of carbon microelectrodes. This ...

Elsevier2013

Electrochemical Push–Pull Scanner with Mass Spectrometry Detection

Hubert Girault, Gunther Wittstock, Fernando Cortes Salazar, Liang Qiao, Dmitry Momotenko, Andreas Stephan Lesch

This manuscript presents a push-pull electrochem. scanner able to image reactivity of initially dry surfaces by scanning electrochem. microscopy (SECM) and to probe mols. present or generated at the surface by mass spectrometry (MS). The proof-of-concept i ...

Amer Chemical Soc2012

Microfluidic Push-Pull Probe for Scanning Electrochemical Microscopy

Hubert Girault, Gunther Wittstock, Fernando Cortes Salazar, Dmitry Momotenko, Andreas Stephan Lesch

This paper presents a microfluidic push-pull probe for scanning electrochemical microscopy (SECM) consisting of a working microelectrode, an integrated counter/reference electrode and two microchannels for pushing and pulling an electrolyte solution to and ...

2011

Seeing Big with Scanning Electrochemical Microscopy

Hubert Girault, Gunther Wittstock, Fernando Cortes Salazar, Dmitry Momotenko, Andreas Stephan Lesch

Specialized microelectrode probes fabricated in a soft polymer film now make it possible to use scanning electrochemical microscopy to image the reactivity of large, corrugated, tilted, and dry surfaces. ...

American Chemical Society2011

Fountain pen for scanning electrochemical microscopy

Hubert Girault, Gunther Wittstock, Fernando Cortes Salazar, Dmitry Momotenko, Andreas Stephan Lesch

A fountain pen probe has been developed to extend the scope of scanning electrochemical microscopy (SECM) experiments to dry surfaces. The fountain pen is fabricated by UV-photoablation of a polyethylene terephthalate (PET) film and consists on one side of ...

Royal Society of Chemistry2010

Soft Microelectrode Linear Array for Scanning Electrochemical Microscopy

Hubert Girault, Gunther Wittstock, Fernando Cortes Salazar, Dmitry Momotenko, Andreas Stephan Lesch

A linear array of eight individual addressable microelectrodes has been developed in order to perform highthroughput scanning electrochemical microscopy (SECM) imaging of large sample areas in contact regime. Similar to previous reports, the soft microelec ...

American Chemical Society2010

Soft Stylus Probes for Scanning Electrochemical Microscopy

Hubert Girault, Anne-Laure Gassner, Mohamad Hojeij, Gunther Wittstock, Fernando Cortes Salazar

A soft stylus microelectrode probe has been developed to carry out scanning electrochemical microscopy (SECM) of rough, tilted, and large substrates in contact mode. It is fabricated by first ablating a microchannel in a polyethylene terephthalate thin fil ...

2009

Scanning Electrochemical Microscopy as a Readout Tool for Protein Electrophoresis

Hubert Girault, Gunther Wittstock

Scanning electrochemical microscopy (SECM) was used to image silver-stained proteins on a poly(vinylidene difluoride) membrane. The method is based on measuring the current at a scanning microelectrode in the feedback mode. The electrochemical feedback is ...

2007