European Fuel Cell Forum 2011

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European Fuel Cell Forum 2011 28 June -1 July 2011, Lucerne Switzerland
A0702
Towards stable catalyst supports
Isotta Cerri, Tetsuo Nagami, Jon Davies and Brian Hayden
Toyota Motor Europe
Advanced Technology Division
Hoge Wei 33
1930 Zaventem
Belgium
Tel.: +32-2-7123189
Fax: +32-2-7123399
Isotta.cerri@toyota-europe.com
Abstract
Despite great progress in enhancing the performance of PEM fuel cells, durability remains
one of the critical issues that need to be solved in order to successfully penetrate the
automotive market.
We have demonstrated that in automotive field tests the durability of the membraneelectrode-assembly
(MEA) plays a major role in the overall lifetime of the stack. Transient
conditions are responsible for MEA performance loss: power (or voltage) cycling increases
the rate of electrocatalyst surface area loss; start-up/shut-down induces membrane
degradation and carbon corrosion. Carbon under PEM fuel cell operating conditions is
thermodynamically unstable and will be oxidized/corroded at potentials near the open
circuit voltage of a fuel cell (about 1.0 V), with the oxidation rate increasing along with
potential. It has been demonstrated that at start- up the lack of hydrogen at the anode is
critical for carbon corrosion at the cathode. Carbon corrosion will finally result in Pt
particles agglomeration and loss of performances.
In the present study we have been focusing on the development of new catalyst support
materials, as alternatives to conventional carbon supports to overcome the corrosion
related issues. We have developed durable catalyst supports, using high throughput
discovery and optimization, with enhanced electrochemical stability and improved
electrical conductivity to sustain the electrochemical reactions.
The present work will investigate the effect of different properties such as the chemical
composition and crystallinity of the newly developed materials on the electrical conductivity
and stability. In the design of the new support we paid special attention to the synergetic
effect of the support on the catalyst, aiming at promoting higher catalyst activity and
stability.
PEMFC Components-Electrodes A07 - 2/10
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European Fuel Cell Forum 2011 28 June -1 July 2011, Lucerne Switzerland
A0703
Continuous preparation of highly active
Pt/CNT catalysts
Alicja Schlange, Antonio Rodolfo Dos Santos, Ulrich Kunz and Thomas Turek
Institute of Chemical Process Engineering
Clausthal University of Technology
Leibnizstr.17
D-38678 Clausthal-Zellerfeld, Germany
Tel.: +49-5323-722187
Fax: +49-5323-722182
lezniak@icvt.tu-clausthal.de
Abstract
Direct methanol fuel cells (DMFs) are considered to be an attractive power source for
portable application because of their simplicity in construction, high energy density and low
emission of pollutants. For their widespread commercialization electrocatalysts with high
metal loading and uniformly metal distribution are needed. To find a suitable method for
catalyst preparation is still a challenge of fuel cell catalyst research, because it can
strongly influence the catalyst morphology, particle size and moreover its catalytic activity.
Commonly fuel cell electrocatalysts are prepared in batch processes using a heat mantle
or an oil bath as a heat source. In this contribution we present the use of a continuously
operated tubular reactor as a novel method for synthesis of carbon nanotube supported
platinum catalysts. The as-prepared catalyst shows uniform dispersion of metal
nanoparticles on the support material, an average crystallite size of 1.77 nm confirmed by
XRD analysis and a Pt loading of 31 wt. %. Excellent electrocatalytic activity towards
oxygen reduction reaction (ORR) of this catalyst was evaluated in a working DMFC
environment. The reached maximum power density of 103 mW cm -2 was 60 % higher than
for Pt/CNT catalyst prepared in a conventional batch process.
PEMFC Components-Electrodes A07 - 3/10