Hydrogen-fueled polymer electrolyte fuel cell (PEFCs) systems are currently utilized as high efficiency, low emission power sources for a variety of applications, most notably for electric vehicles such as the Toyota Mirai. The high cost of platinum, widely used as the electrocatalyst in PEFCs, is one of main barriers to the widespread and economically-viable implementation of fuel cell vehicles. Many research efforts have successfully developed platinum group metal-free (PGM-free) electrocatalysts for the oxygen reduction reaction (ORR), including those in the U.S. Department of Energy, Fuel Cell Technologies Office’s Electrocatalysis Consortium (ElectroCat)^1-3. High-throughput catalyst synthesis, activity evaluation, and performance testing are core activities within ElectroCat aimed at accelerating the discovery and implementation of ORR electrocatalysts. High-throughput catalyst activity screening is accomplished using a newly-developed multi-channel flow double electrode, allowing activity measurements of four catalysts simultaneously deposited on glassy carbon electrodes using an automated robotic catalyst ink dispensing system with a nano-liter injector⁴.

The purpose of this project is to accelerate the development of PGM-free catalysts using high-throughput performance evaluation in a 25-electrode array cell (NuVant) which has a common counter electrode and five independent flow channels. This system allows simultaneous performance testing and characterization of 25 types of catalyst in a membrane-electrode assembly (MEA) with five gas supply manifolds. Electrode fabrication is one of the most challenging steps in the catalyst-coated membrane (CCM) fabrication process for the array cell. A custom-designed heated vacuum table mounted on the computer-controlled XY table is used to make the 25-electrode CCM to avoid shrinkage and swelling of the catalyst layer and the membrane during the fabrication. The nano-pipette automated ink deposition system is being used for precise and even catalyst ink deposition across the small circular array electrodes. Scanning electron microscopy of the electrode is being utilized to confirm uniform and robust microstructures after the direct fabrication method. The 25-electrode set-up can accelerate PGM-free catalyst evaluation and optimization of electrode composition with the additional advantage of minimizing the amount of material required since the area of each electrode in the array is less than 1 cm².

Acknowledgements

This work was supported by the U.S. Department of Energy, Energy Efficiency and Renewable Energy, Fuel Cell Technologies Office under the auspices of the Electrocatalysis Consortium (ElectroCat). Argonne National Laboratory is managed for the U.S Department of Energy by the University of Chicago Argonne, LLC, under contract DE-AC-02-06CH11357.

References

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