Advanced Porous Transport Electrode for High-Performance Proton Exchange Membrane Water Electrolyzers

Abstract

Proton exchange membrane water electrolyzers (PEMWEs) hold great potential for supplying green hydrogen to support extensive energy storage and mobility in a future energy landscape centered on renewable energy sources.1,2 However, their contribution to global hydrogen production is currently limited, mainly due to their comparatively high cost.3 To improve the economic competitiveness of green hydrogen and foster broader market penetration, the Department of Energy (DOE) has launched the Hydrogen Earthshots, aiming for a substantial cost reduction to $2 per kilogram by 2025 and $1 per kilogram for green hydrogen by 2030.4 The high efficiency and prolonged durability are pivotal for the overall performance and cost reduction of the PEMWEs. This requires careful consideration of the interfacial contact between the porous transport layer (PTL) and the anode catalyst layer.5 One option for PEMWEs is to directly coat the anode catalyst layer onto the PTL, forming porous transport electrodes (PTEs). Recent literature suggests that it is feasible to manufacture PTEs with low precious metal loading, demonstrating both high performance and durability.6,7 In this study, an innovative reactive spray deposition technology (RSDT) is used to fabricate PTEs with low PGM loading (0.2 - 0.3 mgPGM cm-2) in both catalyst layers. The RSDT is a flame-based method that combines the synthesis and deposition of the catalyst in a single step, significantly reducing the fabrication time and cost of the membrane electrode assembly (MEA).8–11 The RSDT-fabricated PTEs are coupled with various membranes, and their performance has been assessed and compared to the state-of-the-art MEAs for PEMWEs. In addition, the performance loss in each cell has been studied and discussed in detail. Furthermore, a standard accelerated stress test (AST) protocol has been applied to assess the durability of the RSDT-fabricated MEAs, with one order of magnitude lower PGM loading in their catalyst layers in comparison to the commercial MEAs for PEMWEs.Reference1. Pham, C. Van, Escalera-López, D., Mayrhofer, K., Cherevko, S. & Thiele, S. Essentials of High Performance Water Electrolyzers – From Catalyst Layer Materials to Electrode Engineering. Adv. Energy Mater. 11, (2021).2. Carmo, M., Fritz, D. L., Mergel, J. & Stolten, D. A comprehensive review on PEM water electrolysis. Int. J. Hydrogen Energy 38, 4901–4934 (2013).3. Buttler, A. & Spliethoff, H. Current status of water electrolysis for energy storage, grid balancing, and sector coupling via power-to-gas and power-to-liquids: A review. Renew. Sustain. Energy Rev. 82, 2440–2454 (2018).4. Styapal, S. et al. DOE Update on Hydrogen Shot, RFI Results, and Summary of Hydrogen Provisions. (2021).5. Peng, X. et al. Insights into Interfacial and Bulk Transport Phenomena Affecting Proton Exchange Membrane Water Electrolyzer Performance at Ultra-Low Iridium Loadings. Adv. Sci. 8, (2021).6. Xie, Z. et al. Ionomer-free nanoporous iridium nanosheet electrodes with boosted performance and catalyst utilization for high-efficiency water electrolyzers. Appl. Catal. B Environ. 341, 123298 (2024).7. Lee, J. K. et al. Ionomer-free and recyclable porous-transport electrode for high-performing proton-exchange-membrane water electrolysis. Nat. Commun. 14, 1–11 (2023).8. Zeng, Z. et al. Advanced nickel-based catalysts for the hydrogen oxidation reaction in alkaline media synthesized by reactive spray deposition technology: Study of the effect of particle size. Int. J. Hydrogen Energy 1–12 (2023) doi:10.1016/j.ijhydene.2023.03.249.9. Zeng, Z. et al. Degradation Mechanisms in Advanced MEAs for PEM Water Electrolyzers Fabricated by Reactive Spray Deposition Technology. J. Electrochem. Soc. 169, 054536 (2022).10. Xing, J. et al. Long-term durability test of highly efficient membrane electrode assemblies for anion exchange membrane seawater electrolyzers. J. Power Sources 558, 232564 (2023).11. Mirshekari, G. et al. High-performance and cost-effective membrane electrode assemblies for advanced proton exchange membrane water electrolyzers: Long-term durability assessment. Int. J. Hydrogen Energy 46, 1526–1539 (2021).