polymer electrolyte fuel cell; PEFC; degradation; platinum; carbon; corrosion; electro-catalysis; electrochemistry; scanning tunneling microscopy; x-ray photoelectron spectroscopy
Guzenko VA, Ziegler J, Savouchkina A, Padeste C, David C (2011), Fabrication of large scale arrays of metallic nanodots by means of high resolution e-beam lithography, in MICROELECTRONIC ENGINEERING
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Savouchkina A, Foelske-Schmitz A, Guzenko VA, Weingarth D, Scherer GG, Wokaun A, Kotz R (2011), In situ STM study of Pt-nanodot arrays on HOPG prepared by electron-beam lithography, in ELECTROCHEMISTRY COMMUNICATIONS
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Savouchkina A, Foelske-Schmitz A, Scherer GG, Wokaun A, Kötz R (2011), Study of Platinum Deposition on Untreated and Thermally Modified Glassy Carbon, in JOURNAL OF THE ELECTROCHEMICAL SOCIETY
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Savouchkina A, Foelske-Schmitz A, Kötz R, Wokaun A, Scherer GG, Padeste C, Ziegler J, Auzelyte V, Solak HH (2010), Extreme ultraviolet interference lithography for generation of platinum nanoparticles on glassy carbon, in ECS Transactions
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The polymer electrolyte fuel cell (PEFC) has been proven to be an alternative power source for stationary and portable applications as well as for sustainable individual mobility. Currently, cost, reliability, and lifetime are the most important issues for practical use of this power source. In PEFCs the electrochemical reactions occur at catalyst surfaces of a three-phase boundary (electrolyte / electrode / gasphase) at operating temperatures between 60 and 100°C. Due to high efficiency and potentially high corrosion resistance the catalyst used in conventional PEFCs consists of nanoparticles of platinum and its alloys dispersed on a carbon support, and, therefore, is one of the major cost drivers. As a consequence, one key challenge in fuel cell development is to decrease the platinum content by maximizing its utilization and lifetime. Under steady state conditions platinum and carbon show high corrosion resistance. However, depending on the duty cycle, it is proposed that a considerable loss in cell performance refers to sinter and/or corrosion processes of the catalyst and/or its support. Investigations leading to an understanding of these processes are of fundamental interest for the optimization of the catalyst. In most of the relevant studies in this research field complex composite electrodes under different working conditions (temperature, time, potential, stoichiometry etc.) were investigated. Systematic studies in which state-of-the-art in situ analytical methods are applied to study the corrosion and sinter properties of model materials are missing. In this project degradation mechanisms on model electrodes that consist of platinum nanoparticles with various sizes (from 1 to 100 nm) dispersed on defined carbon substrates will be systematically studied using in situ electrochemical scanning probe microscopy in combination with x-ray photoelectron spectroscopy. This approach will allow us to investigate chemical and structural changes in dependence on the substrate, particle size and composition, and applied electrode potential in real time and down to the atomic scale. The model electrodes serving the larger particles (> 10nm) are going to be prepared in collaboration with the Laboratory for Micro- and Nanotechnology at PSI aiming to produce periodic dot-structures via extreme ultraviolet interference at the unique XIL-beamline at the SLS. The smaller particles will consist of colloids and are going to be prepared in collaboration with H. Schulenburg from the Fuel Cells Group of the Electrochemistry Laboratory and G. Khelashvili from H. Bönnemanns Group at the Forschungszentrum Karlsruhe.Overall, the collected data shall lead to a basic understanding of the degradation mechanisms that take place on carbon and platinum under defined reaction conditions (potential, time, temperature) and might help to design new catalysts by adjusting both the support and the catalytically active compound.