CAREER: Mechanisms of Ion Transport in Ionomer-Free Electrodes

项目负责人：Zenyuk， Iryna v .提案号：1652445机构：塔夫茨大学标题：无离聚体电极中的离子传输机制聚合物电解质燃料电池（PEFCs）作为一种可持续能源技术具有巨大的前景，并且开发低铂（Pt）负载的新电极设计具有显著的成本动机。然而，最近关于传统的、碳支撑的、减少pt负载的PEFC电极的报道表明，在高电流密度下，由于氧通过薄膜离聚体的传输阻力，导致了显著的性能损失。这些发现促使人们寻找不依赖于离子分子的质子传导的替代电极设计。纳米结构薄膜电极和其他几种扩展表面积电极已经显示出很好的功率密度和耐用性，然而潜在的离子传输机制和相关的反应动力学途径仍然不清楚。该项目旨在确定限制使用薄膜电极的pefc性能的具体因素，并允许在克服这些障碍方面取得进展。PI计划将研究成果整合到教学中，并为包括代表性不足的少数民族在内的各种K-12学生开展广泛的教育和推广活动，以培养对可再生能源和STEM职业的兴趣。本研究有三个主要目标：(1)阐明离子在水填充Pt和分散的碳负载Pt电极中传输的基本机制。(2)建立氧还原反应（ORR）电流下离子传导机理的操作窗口（电流、温度和相对湿度）。(3)确定在充满水的电极中发生ORR的参与离子和机制，并创建定制的电极设计以提高ORR率。竞争离子输运机制的分离将通过离地四点探针实验结合电化学技术和建模研究来完成。所提出的工作有可能促进目前对无离聚体PEFC电极中离子传输机制的理解。

PI: Zenyuk, Iryna V.Proposal Number: 1652445Institution: Tufts University Title: CAREER: Mechanisms of Ion Transport in Ionomer-Free ElectrodesPolymer electrolyte fuel cells (PEFCs) hold great promise as a sustainable energy technology, and there is significant cost motivation to develop new electrode designs with low platinum (Pt) loading. However, recent reports on conventional, carbon-supported, reduced Pt-loading PEFC electrodes have shown significant performance losses due to oxygen transport resistance through a thin-film ionomer at high current-densities. These findings have motivated a search for alternative electrode designs that do not rely on ionomers for proton conduction. Nano-structured thin-film electrodes and several other extended-surface area electrodes have demonstrated promising power densities and durability, however underlying ion transport mechanisms and associated reaction kinetic pathways are still ill understood. The proposed project aims to determine the specific factors which limit performance of PEFCs using thin-film electrodes and allow for work to progress on overcoming these hurdles. The PI plans to integrate research findings into teaching and develop a broad range of educational and outreach activities to a diverse range of K-12 students, including underrepresented minorities, to foster excitement about renewable-energy and STEM careers.The proposed research has three main objectives: (1) Elucidate the fundamental mechanisms of ion transport in water-filled Pt and dispersed, carbon-supported Pt electrodes. (2) Establish the operational window (current, temperature and relative humidity) for ion-conduction mechanisms under oxygen reduction reaction (ORR) currents. (3) Determine the participating ions and mechanisms that occur in ORR in water-filled electrodes and create tailored electrode designs to enhance the rate of ORR. The separation of competing ion transport mechanisms will be accomplished through ex-situ four-point probe experiments combined with in-operando electrochemical techniques and modeling studies. The proposed work has the potential to advance the current understanding of the mechanisms of ion transport in ionomer-free PEFC electrodes.