Overview of SMARTCAT - Systematic, Material-oriented Approach using Rational design to develop break-Through Catalyst s for commercial automotive PEMFC
Résumé
In frame of SMARTCat project, the consortium will build a new concept of electrodes based on new catalyst design
(ternary alloyed/core-shell clusters) deposited on a new high temperature operation efficient support.
In order to enhance the fundamental understanding and determine the optimal composition and geometry of the
clusters, advanced computational techniques will be used in direct combination with electrochemical analysis of the
prepared catalysts. The use of deposition by plasma sputtering on alternative non-carbon support materials will
ensure the reproducible properties of the catalytic layers. Plasma technology is now a well established, robust,
clean, and economical process for thin film technologies.
Well-defined chemical synthesis methods will also be used prior for defining the best catalysts. In addition, MEA
preparation, testing, and MEA automated fabrication will complete the new concepts of catalysts with a
considerably lowered Pt content (below 0.01 mgcm-2 and as low as 0.001 mgcm-2) and alternative support. The final
goal will be to deliver a competitive and industrially scalable new design of PEMFC suitable for automotive
applications.
SMARTCat address the following objectives:
• Deliver specifications/requirements for reaching the technical goals as a roadmap.
• Design new efficient catalyst architecture
• Establish a support selection criterion based on physico-chemical characterization and modelling for defining
the most suited electrode support to the defined catalytic system
• Assess the robustness regarding operation conditions and fuel cell efficiency
• Enable to automate the MEA production using state of the art (< 100°C) and high temperature membranes
(120°C)
• Build efficient short-stack required for competitive automotive fuel cell operation
• Low cost process and low Pt content will dramatically reduce the fuel cell cost, and which will lead to
economically suitable fuel cells for automotive application
Among the main findings, up-to-date SMARTCat major outputs are:
1. The results regarding the best tri-metallic catalysts obtained by a combined experiment-theory common work.
In this context PtPdAu tri-metallic catalysts have been evaluated. It has been found that contrary to the
literature, this system has the drawback to allow Au migration on the surface, when concentration is higher
than 25%. Thus, this will reduce the ORR activity. Consequently reducing Pt noble catalyst content will be
difficult. PtNiAu are thus preferred in the present time and are further investigated.
2. Tin Oxide (SnO2) does not have sufficient electronic conductivity, and must therefore be modified. The
properties of this material was tailored by (i) different doping (e.g. niobium (Nb), antimony (Sb)) to achieve
sufficient n-type electronic conductivity, (ii) different synthesis techniques to tailor the particle size, surface
area and pore size distribution of the support materials. Two different techniques (co-precipitation and flame
spray pyrolysis) with preferable potential to be up scaled are used. In parallel, theoretical research has been
focused on (i) identification of the correct model system for the SnO2/Pt interface and the correct
computational setup for the description of its electronic structure, (ii) the computational modelling of the
interface between Pt(111) and SnO2(110) and the role of migration and localization of Sb in SnO2at this
interface, (iii) segregation of the doping elements (Sb and Nb) at the SnO2/Pt interface, and (iv) the study of the
influence of segregation on the transport properties of the whole system.
3. High temperature polymer membrane is currently developed within the project. Monomer, polymer synthesis is
well in hand (a 1 kg campaign), thin unreinforced film preparation and curing at lab scale (100 – 150 cm2)
proceeds well; membrane activation with acid is not yet under satisfactory control.