Mechanistic interactions in polymer electrolyte fuel cell catalyst layer degradation
Mechanistic interactions in polymer electrolyte fuel cell catalyst layer degradation
复制标题
聚合物电解质燃料电池催化剂层降解的机理相互作用
DOI：
10.1039/d2ta02177c
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发表时间：
2022
影响因子：
11.9
通讯作者：
Mukherjee, Partha P.
中科院分区：
文献类型：
--
作者：
Goswami, Navneet;Grunewald, Jonathan B.;Fuller, Thomas F.;Mukherjee, Partha P.
由于铂 (Pt) 催化剂的降解，聚合物电解质燃料电池 (PEFC) 在循环过程中表现出相当大的性能衰减，导致宝贵的电化学活性表面积的损失。因此，保留催化剂库存对于持续的阴极氧还原反应 (ORR) 和延长 PEFC 的预期寿命至关重要。我们展示了一个热动力学模型，该模型认识到铂颗粒溶解-再沉淀和氧化物形成等过程，并结合电化学反应传输模型，以深入了解界面尺度上的有害现象。催化剂层环境中颗粒老化的非均质性质通过粗化-收缩区域来描述，并且通过公制的起始时间从直径仓的溶解亲和力进一步理解不稳定性特征。高温和完全潮湿条件下的严重降解与局部传输阻力和临界瞬态交织在一起，其中催化剂纳米颗粒达到极限直径阶段。我们通过电极中离聚物体积分数和颗粒分布平均尺寸的变化进一步揭示了降解性能特征。研究发现，动力学和传输特性很大程度上取决于两种模式的相互作用——一种模式导致催化剂纳米颗粒的耗尽，另一种模式则导致催化剂粗化。
Polymer Electrolyte Fuel Cells (PEFCs) exhibit considerable performance decay with cycling owing to the degradation of platinum (Pt) catalysts, resulting in the loss of the valuable electrochemically active surface area. Catalyst inventory retention is thus a necessity for a sustained cathodic oxygen reduction reaction (ORR) and to ameliorate the life expectancy of PEFCs. We demonstrate a thermo-kinetic model cognizant of processes like platinum particle dissolution–reprecipitation and oxide formation coupled with an electrochemical reactive transport model to derive mechanistic insights into the deleterious phenomena at the interfacial scale. The heterogeneous nature of particle aging in a catalyst layer environment is delineated through coarsening–shrinking zones and further comprehension of instability signatures is developed from the dissolution affinity of diameter bins through a metric, onset time. The severe degradation at high temperature and under fully humidified conditions is intertwined with the local transport resistance and the critical transient, where the catalyst nanoparticles reach a limiting diameter stage. We further reveal the degradation-performance characteristics through variation in the ionomer volume fraction and the mean size of the particle distribution in the electrode. It has been found that the kinetic and transport characteristics are crucially dependent on the interplay of two modes – one leading to the depletion of the catalyst nanoparticles and the other that emanates from catalyst coarsening.