Robust Fuel Cell Electrodes: Pt Thin Film Catalysts for Anode Reversal Tolerance

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In recent years, polymer electrolyte membrane fuel cells (PEMFCs) have garnered significant attention due to their remarkable attributes including high power density, energy efficiency, and zero-emission characteristics. This surge in interest has primarily been driven by the potential of PEMFC-powered fuel cell electric vehicles (FCEVs) to substantially reduce carbon dioxide emissions in the transportation sector, thereby propelling the advancement of the hydrogen economy on a global scale. However, the widespread commercialization of FCEVs hinges upon addressing key challenges surrounding the durability and resilience of fuel cell systems. One critical issue that has emerged is the phenomenon of hydrogen starvation in the anode, particularly during start-up/shutdown or cold start scenarios, which can lead to rapid and severe degradation of PEMFC performance and durability through cell reversal. This degradation manifests quickly, often within minutes, resulting in abrupt cell failure. Extensive prior research has been devoted to unraveling the mechanisms underlying degradation induced by hydrogen starvation and cell reversal in PEMFCs, with the goal of identifying effective mitigation strategies to minimize damage to membrane electrode assembly (MEA) components. In this study, we introduce an innovative materials approach aimed at mitigating cell damage by employing a thin film Pt anode catalyst supported on Nafion nanowires in a co-axial configuration, referred to as coaxial nanowire electrode (CANE). Leveraging the high roughness of Nafion nanowires, CANE eliminates the need for conventional carbon support and exhibits exceptional tolerance to reversal-induced stress. We present a comprehensive evaluation of CANE as a reversal-tolerant anode, comparing its performance to that of conventional supported catalysts (Pt/C). Furthermore, we explore the potential for further enhancing durability by integrating iridium with the CANE anode. Finally, we will delve into our efforts to evaluate the feasibility of implementing this concept in structures that can be manufactured at scale. This research contributes to the ongoing efforts to enhance the robustness and longevity of PEMFC systems, thereby advancing the prospects of FCEVs as a sustainable and viable solution for future transportation needs. Acknowledgement This research was supported by the Hydrogen and Fuel Cell Technologies Office (HFTO), Office of Energy Efficiency and Renewable Energy, US Department of Energy (DOE) through the Million Mile Fuel Cell Truck (M2FCT) consortia, technology managers G. Kleen and D. Papageorgopoulos. Authors would also like to acknowledge support for this work from the Laboratory Directed Research and Development (LDRD) program at Los Alamos National Laboratory (LANL) (2020200DR).

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