Catalyst degradation in PEM fuel cells: from physical understanding to mitigation

我们提出了一个为期三年的研究合作，旨在了解和减轻催化剂降解机制的聚合物电解质燃料电池（PEFC）的汽车应用。主要模块侧重于开发一套一致的建模工具。建模将与实验和测试工作密切协调，由学术界和工业界的合作者进行。汽车PEFC在其使用寿命期间经历数千次正常操作事件，例如启动/关闭、加速、稳定爬升或怠速。在此生命周期内需要保持严格的性能水平。相应地，工业界和政府对退化设定了严格的限制。因此，研究活动的重点是揭示铂基电催化剂系统的电催化活性、稳定性和成本的相互关联的方面。计划的合作和跨学科研究计划的理论部分将产生催化剂降解现象的一致理解。 该研究将跨越相关层次的尺度，包括原子的扩展表面催化剂的研究，介观研究模型系统的催化剂纳米粒子分布在平原基板表面，宏观研究的全功能阴极催化剂层在PEFC。模型将得到证实，并通过系统的比较与非原位实验和原位测试单个操作的燃料电池连续细化。将探讨不同的反应条件和加速应力试验的典型电压变化方案对催化剂质量损失和再分布的影响。预期的成果包括对燃料电池如何降解的基本理解，对材料参数和局部反应条件如何影响耐久性的诊断理解，以及对操作系统管理可以做些什么来减轻压力的实际理解。这种理解将导致一个列表的催化剂层的结构设计和微调的操作条件，以延长在PEFC的Pt基催化剂的寿命的实用建议。

We propose a three-year research collaboration designed to understand and mitigate catalyst degradation mechanisms in polymer electrolyte fuel cells (PEFC) for automotive applications. The main modules focus on the development of a consistent suite of modeling tools. Modeling will be conducted in close coordination with experimental and testing work, conducted by collaborators in academia and industry. An automotive PEFC, during its lifetime, is subjected to thousands of normal operational events such as start-up/shut-down, acceleration, steady climbs, or idling. Stringent levels of performance need to be maintained over this lifetime. Correspondingly, industry and governments have set strict limits on degradation. Therefore, activities in research focus on unraveling interrelated aspects of electrocatalytic activity, stability and cost of Platinum-based electrocatalyst systems. Theoretical portions of the planned collaborative and interdisciplinary research program will produce a consistent understanding of catalyst degradation phenomena. The research will span the relevant hierarchy of scales, encompassing atomistic studies on extended surface catalysts, mesoscopic studies on model systems of catalyst nanoparticles distributed at plain substrate surfaces, and macroscopic studies on fully functional cathode catalyst layers in PEFC. Models will be corroborated and successively refined by systematic comparison with both ex situ experiments and in situ tests on single operational fuel cells. The impact of varying reaction conditions and typical voltage variation protocols of accelerated stress tests on catalyst mass loss and redistribution will be explored. The anticipated outcomes include fundamental understanding of how fuel cells degrade, diagnostic understanding of how materials parameters and local reaction conditions affect durability, and practical understanding of what operational system management can do to mitigate stressors. This understanding will lead to a list of practical recommendations for structural design of catalyst layers and fine-tuning of operating conditions in order to extend the lifetime of Pt-based catalysts in PEFC.