Characterisation of MEAs with PEGASUS catalyst by operando neutron radiography

In March 2021 CEA characterised a set of MEAs integrating PMG-free catalysts developed by ARMINES and CEA within the PEGASUS project under a neutron beam at the Institut Laue-Langevin (ILL) in Grenoble in France. This experiment allowed the imaging of the liquid water content in the MEA in operando, meaning while delivering current.

Thanks to the progress made in the frame of the long-term collaboration between the CEA and ILL, an im-pressive spatial resolution of 5*15 μm2 and a time resolution of 30 s could be achieved to track the liquid water repartition. This will lead to a better understanding of the water management in MEAs integrating PGM-free catalysts at the cathode and more generally to a better understanding of water management in MEAs based on thick cathodes. This will also allow giving recommendations to improve the active-layer structure and enhance the performance of the MEA.

To perform this experiment and to reach the targeted resolution:

• a new cell with dedicated hardware design was developed,
• a dedicated hydrogen test station fitting the ILL requirement was used, and
• MEAs integrating the latest PGM-free catalysts from PEGASUS were fabricated.

Connection of the cell in the neutron-radiography setup.

Characterisation of N environment in PEGASUS Fe/N/C catalysts by soft x-ray absorption spectroscopy

In collaboration with a research group in Diamond Light Source Synchrotron in Oxfordshire in the UK, CSIC is carrying out soft x-ray absorption spectroscopy (NEXAFS) studies to unveil the architecture of the nitro-gen atoms’ environments in Fe/N/C catalysts and their evolution during the oxygen reduction reaction (ORR), which is the cathode reaction of the fuel cell. This hitherto rather unexplored approach provides new insights of the actual active N and FeN environments and their durability and stability under the
reaction. The group has already studied several catalysts (J. Power Sources 490 (2021) 229487), and they are currently performing more experiments on different PEGASUS catalysts.

Quantification of active sites and determination of turnover frequency of PEGASUS Fe/N/C catalysts

Determining the content of active sites in Fe/N/C catalysts is indispensable to assess their intrinsic activity. This can be done by chemisorption of probe molecules. The CSIC group is studying the chemisorption of CO molecules at low temperature over Fe atoms and chemisorption of NO at room temperature. The results obtained are still not conclusive; however, the evolution of the number of active sites and the turnover fre-quency (TOF) obtained are in line with the results obtained for the ORR activity.

PEGASUS technical workshop

An online workshop titled PGM Free Catalysts for ORR for PEMFC was organised under the auspices of the PEGASUS project on 14–15 June 2021. The objectives of the workshop were to present the results obtained in PEGASUS and in other international projects working on PGM-free catalysts, and to share visions on PGM-free electrocatalysis for PEMFC application. The workshop took place over two half days and featured presentations by the PEGASUS partners and invited talks by prominent scholars in the field of PGM-free electrocatalysis, among those the coordinators of the EU H2020 FCH JU project CRESCENDO and the US DoE project ElectroCat.

PEGASUS dissemination

PEGASUS activities and results have been presented at eight scientific events as well as in four popular ra-dio and tv programmes. Six papers have been published in international scientific journals, another manu-script has been submitted, and around 14 oral presentations have been given and 10 posters presented in international and national conferences.

Project termination 30-Jun-2021

After a five-month extension necessitated by the lockdowns installed during the COVID-19 pandemic, the PEGASUS project terminated on 30 June 2021, 41 months after it was launched. The final reporting is now being made, in order to submit all required documentation by the deadline of ultimo August 2021.

PEGASUS aims at developing proton-exchange membrane fuel cells (PEMFCs) with platinum-free cathode to accelerate the widespreading of hydrogen vehicles. It is a European project supported by the Horizon 2020 Fuel Cells and Hydrogen Joint Undertaking (FCH JU) under contract no. 779550. It started in February 2018 and is coordinated by CEA (F). Other partners are DLR (D), TUM (D), CSIC (E), ARMINES (F), HERAEUS (D), IRD (DK) and TOYOTA (B).