(Invited) Catalysts, Inks and Electrodes for PEM Water Electrolysis: Scalable Approach for Highly Performed Catalyst Layer Fabrication

The majority of commercially available anodic electrocatalysts for Low Temperature PEM Water Electrolyzers are based on unsupported iridium-based materials. These electrocatalysts can be amorphous or crystalline metallic, oxidic, and/or hydroxide-derived compounds. The planned worldwide installations of electrolyzers (on the order of tens of Gigawatts per year) will require manufacturing of Membrane Electrode Assemblies (MEAs) via highly scalable methods, one of which is Roll-2-Roll production (R2R) [1, 2]. In contrast to spraying techniques, R2R requires the utilization of inks with a higher content of solids, which in the case of extremely dense Ir-based materials may cause a sedimentation of suspended electrocatalysts resulting in overall ink destabilization. In the presented work a systematic study of ink stability with commercial IrO 2 catalysts over a period of 14 days was performed. During this period of time the minimal redispersion of slurries was done to mimic realistic conditions of inks aging. The inks were comprehensively characterized by rheological measurements, zeta potential, particle size distribution (Dynamic Light Scattering) and inks density. A series of decal electrodes was fabricated using Baker bar coating approach (a model of R2R production) and coatings were characterized by contact angle, X-Ray Photoelectron Spectroscopy and Transmission Electron Microscopy. Detailed electrochemical performance analysis including the separation of voltage losses [3] via Electrochemical Impedance Spectroscopy was performed to compare MEA performance with aging time. Acknowledgements and Statements. The authors acknowledge financial support from M2FCT and H2NEW consortia. References. [1] J. Sharma, X. Lyu, T. Reshetenko, G. Polizos, K. Livingston, J. Li, D. L. Wood, A. Serov "Catalyst layer formulations for slot-die coating of PEM fuel cell electrodes" Int. Journal of Hydrogen Energy 47 (2022) 35838-3585. [2] E. B. Creel, K. Tjiptowidjojo, J. A. Lee, K. M. Livingston, P. R. Schunk, N. S. Bell, A. Serov, D. L. Wood III "Slot-Die-Coating Operability Windows for Polymer Electrolyte Membrane Fuel Cell Cathode Catalyst Layers" J. of Colloid and Interface Science 610 (2022) 474-485. [3] A. Dizon et. al “Advanced Voltage Break Down Analysis by Statistical Open-Source Tool Case Study Based on Polymer Electrolyte Water Electrolysis”, ECS Abstract 242 (2022)