D2.1: Operating property table for MEA and test protocols
The following document is summarizing specifications for MEA development within the CATAPULT project and providing test parameters for the basic components as basis for the material evaluation within the project. Besides input of internal test protocols provided by the WP partners, harmonization efforts presently on the way by the DOE and the EU (JRC) are also considered.
Definition of fuel cell specifications and test protocols is an onâgoing continuous process; therefore regular updates to this document will be given during the project, if necessary.
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D4.1: Fibrous Pt Catalysts Created With Ald-Deposited Pt On Oxide, Carbide Or Nitride Surface Tie Layers Where The Pt Deposits Extend Over The Surface In Large Contiguous Islands Or As Continuous Films
It is shown that platinum can be deposited by atomic layer deposition onto conductive oxide and nitride surfaces. The platinum extends across the surface in large flat islands which become contiguous at higher loadings. It has been found that a conductive oxide surface gives contiguous islands at a lower loading than a conductive nitride surface. It has also been demonstrated that ALD can be carried out on nanofibrous supports. If the nanofibres are carbon based they can be coated as intact webs. For oxide nanofibres, existing techniques suitable for powders will have to be adopted due to the extreme fragility of the fibres.
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D4.2: Wet electrochemical test for measuring specific and mass activity of fibrous ald-catalysed materials
A Rotating Disc Electrode (RDE) method for wet electrochemical testing of fibrous Pt ALD catalysed materials is described. The method is validated by the testing of standard nano-particulate Pt supported on carbon. The specific activity of the ALD Pt on the fibrous supports was approximately 3 times greater than for the Pt nano-particles supported on carbon. The requirements of Deliverable D4.2 have been met.
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D4.4: Demonstration of Pt-catalysed non-carbon support with higher mass activity than conventional Pt/C nanoparticles and in excess of 0.15 A/Mg Pt
The milestone associated with this deliverable (MS2) is intended as a target to assess the catalytic activity of the novel catalysts produced in this project. The key objective is to determine that the activity is sufficient to make the real goal of the project, a reduction in the mass of platinum per Watt of useful power at the end of life of an MEA, realisable through optimisation of the catalyst layer structure. As can be seen from the data presented above, the precise determination of fuel cell relevant oxygen reduction activity is not straightforward because of variability of results within a particular technique and because of discrepancies between the different techniques. The objective of the work reported in this deliverable was that the mass activity should be both higher than 0.15 A/mg Pt and also higher than conventional Pt/C nanoparticles. One of the materials above achieved 0.15 A/mg Pt, whilst a completely different one showed activity higher than Pt/C nanoparticles.
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D4.5: Demonstration of 0.1 g Pt /kW using novel Pt-based catalysts on a non-carbon support
A novel catalyst design, selected on the basis of previous ex-situ electrochemical characterisation, has been incorporated into an MEA and tested under automotive relevant conditions in a fuel cell. The data presented in this report is prior to any optimisation of the catalyst layer composition and, as a result, the performance of the MEA is only moderate. The novel catalyst does, however, display a step-change improvement in stability over the current international state of the art. For conventional catalysts, a halving in mass activity is typical in accelerated testing, but for the new catalyst no performance is lost. This means that for a material of this type to meet the end of life performance targets, there is no need for ‘excess’ mass activity at the beginning of life.
The stable, novel MEA created here achieves 0.2 g Pt / kW, compared to a project target of 0.1 g Pt/kW, but if the high mass activity achieved with the best catalyst of this type could be realised in an MEA, the level of performance achieved with the un-optimised MEA in this report suggests that an optimised MEA could meet or exceed the project
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D4.6: Demonstration in an MEA of a hybrid catalyst layer achieving >0.25 A/mg Pt
Non-PGM S-MOF derived Fe-NC catalysts were combined with conventional Pt on carbon black catalysts into hybrid cathode catalyst layers and incorporated into MEAs that were tested under automotive-relevant conditions. The performance of the best MEA was slightly less than that which would be expected from the Pt on carbon catalyst in the absence of the non-PGM catalyst. It is shown that this is due to a reduction in the accessibility of the Pt on carbon catalyst, which reduces its effectiveness in the mixed layer at the composition used in this work. The results obtained show that addition of
high ionomer levels is beneficial and it is possible that even more would increase performance further. The hybrid layer performance also improves strongly with time on test, so a different break-in procedure may also give a much higher performance. In general, however, it is thought that the lack of structure in the non-PGM catalyst will limit the performance of hybrid layers and this should be addressed in future work. Work on hybrid catalysts formed from non-PGM Fe-N-C catalysts with small (<2%) additions of Pt from WP5 is also reported here and shows that although the added Pt is not active for the ORR, the stability of the hybrid catalyst is significantly improved. It is hypothesised that this is due to benign decomposition of hydrogen peroxide by the added Pt. The peroxide is formed at the Fe catalytic sites and causes site degradation in the absence of the Pt. The performance of the layers formed with the hybrid catalysts should also be improved by re-structuring of the layers. Further reductions in Pt content or increases in non-PGM catalyst activity would be needed however to hit the target of 0.25 A/mgPt.
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D5.1: Sacrificial-MOF based non-PGM preparation and characterisation including RDE first non-PGM MEA preparation and PEMFC evaluation
Three series of metal organic frameworks (MOFs) have been synthesized and evaluated for the synthesis of Fe-N-C catalysts obtained via the sacrificial approach. The synthesis of targeted MOF materials has been supported by X-ray diffractograms, NMR measurements and experimental isotherms, as well as structural models enabling us to calculate XRD patterns and isotherms
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D5.3: IL-derived non-PGM catalysts synthesis and characterisation including RDE Pristine MOF synthesis, characterisation, electrochemical evaluation, first selection
A one-pot approach through direct pyrolysis of a nitrogen-rich ionic liquid (IL) was used for synthesis of N-doped carbon. Carbonisation of IL in the presence of Fe resulted in a highly graphitised carbonaceous material which was tested for oxygen reduction in acid medium under rotating disk and fuel cell conditions. Accordingly, IL was impregnated with 1 wt% of Fe and pyrolysed under argon at three different temperatures, 500, 900 and 1100 °C. The carbonaceous material showed different activity regarding the pyrolysed temperature. While the IL-500 °C has no activity in acid electrolyte, the
samples pyrolysed at 900 and 1100 °C showed much improved activity, comparable to our internal reference Fe-N-C material when measured in pH 1 aqueous electrolyte.
However, it has to be noted that the IL-derived samples are more limited by O2 diffusion in the catalytic layer, as seen from the long transition from the kinetic control to full diffusion control outside the active layer. In order to improve the porous properties of the carbonised IL, the best performing catalyst, pyrolysed at 1100 °C in argon, was post-treated in NH3 at 950 °C and tested in a fuel cell. However, the performance of the IL derived catalyst showed very low activity in kinetic and diffusion region, even after NH3-treatment.
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D5.4: Final S-MOF based, P-MOF and IL-derived non-PGM formulations and comparative assessment of performance and stability with regard to automotive targets
Fe-N-C catalysts derived from sacrificial metal organic frameworks (MOF) or ionic liquids as well as pristine metal organic frameworks stabilized by graphene oxide were prepared and compared for their oxygen reduction activity. In acid medium, the activity was highest for Fe-N-C catalysts prepared via the sacrificial MOF approach. Within the subfamily of zeolitic imidazolate frameworks (ZIF), structure-property relationships between ZIF structural parameters and activity of pyrolyzed Fe-N-C catalysts was established, and enabled us identifying novel ZIF structures with higher activity than the state of art, previously obtained with the ZIF-8 structure. Some other MOFs were also found to follow these structure property relationships, and two other MOFs lead to higher activity than obtained with ZIF-8. The stabilization of Fe-N-C catalysts by low Pt content (1-2%) was confirmed for Arpyrolyzed or Ar-H2 pyrolyzed Fe-N-C catalysts.
The most active Fe-N-C catalysts prepared including a pyrolysis in NH3 were not stabilized by such low Pt content, possibly due to intrinsic effects of the increased micropore surface area of NH3 pyrolysed Fe-N-C catalysts. Further reduction in the Pt content needed to stabilize Fe- N-C catalysts is desired, while the intrinsic ORR activity of Fe-N-C catalysts that are stabilized by ultralow amounts of Pt must be improved.
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D6.1: Energetics of the ORR reaction mechanism on low-index Pt electrode surfaces described
Computational modelling can provide important insights into chemical reactions in both applied and fundamental fields of research. One of the most critical processes needed in practical renewable energy sources is the oxygen reduction reaction (ORR). Besides being the key process in combustion and corrosion, the ORR has an elusive mechanism that may proceed in a number of complicated reaction steps in electrochemical fuel cells. Indeed, the mechanism of the ORR on highly studied Pt(111) electrodes has been the subject of interest and debate for decades. Herein, we report quantum mechanical density functional theory calculations on the oxygen reduction reaction (ORR) on Pt(111) electrodes and its dependence on environmental parameters, such as solvent, thermodynamic energies, and the presence of an external electrode potential. This approach can, in principle, be applied to other equally complicated investigations of other surfaces or electrochemical reactions.
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D6.2: Kinetic model of the OR under reaction conditions
DFT calculations are used to identify possible ORR reaction mechanisms, allowing the construction of a simple kinetic model to gain qualitative information about contribution of the individual pathways to the overall ORR. Using the calculated activation barriers, a microkinetic model for the water formation in gas-phase is established and the influence of temperature and partial pressure of the reactants on the reaction rates and thus on the preferred mechanism, is investigated.
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D7.1: Project Website
The CATAPULT project website is designed to fulfil project communication and dissemination needs in the direction of the whole scientific community and the public through relevant information including:
project overall objectives, partner & work packages information
project activities: news, meetings, publications
project resources: links, related events
project contact information
All the partners will collectively participate in the dissemination objective of the website by providing up-to-date information
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D7.2: Organisation of an International Workshop
CATAPULT organised a highly successful international conference on the challenges of reduced Pt loading and Pt-free catalysts for oxygen reduction in fuel cells at La Grande Motte in France, 13-16 September 2015. Attended by close to 170 international participants, it provided the opportunity to apprise the state of the art, showcase CATAPULT results and interact with several other FCH-JU funded projects, three of which – CATHCAT, SMARTCAT and NANOCAT were invited to share a special session with CATAPULT dedicated to low Pt cathodes. The conference was preceded by a Fuel Cells Fundamentals Short Course attended by 41 participants from Europe, Asia and the Americas.
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D7.3: Education Actions
This deliverable provides a list of education actions carried out by CATAPULT partners towards a non-specialist public and to students. Such actions were particularly reinforced during the CATAPULT international conference (EFCD2016, 13-16 September 2016, La Grande Motte, France) with a Fuel Cell Short Course and a special session in collaboration with three other running FCH-JU projects.
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D7.4: Plan for dissemination activities
This deliverable report provides a plan for further dissemination and for the use of knowledge and results after the end of the project. For all the partners, a list of publications that have been planned for the next months is given. CATAPULT project web site update and maintenance are discussed. An updated brochure including the final project output from CATAPULT is planned. The impact of the
activities carried out in the project is elucidated. Exploitation of the project results and future cooperation are also discussed.
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