Connectivity and ION Conductions in Fuel Cell Membranes Probed by Tunneling Atomic Force Microscopy

在化学系化学测量和成像项目的支持下，以及材料研究系聚合物项目的共同资助下，加州大学圣巴巴拉分校的Steven Buratto教授和他的团队正在利用导电原子力显微镜（c-AFM）对质子交换膜（PEM）中的离子电导和孔连通性进行成像。在纳米长度尺度和单个孔道水平上用于PEM燃料电池。 PEM燃料电池使用电化学电池将化学能转化为电能，可用作高效电源，提供高功率密度和低环境影响。燃料电池性能的关键是聚合物电解质膜，它是一种有效的质子导体，但电绝缘体。 详细了解质子传导，在负责运输的化学领域的大小和分布方面，对于全面了解燃料电池性能和提高性能的系统方法至关重要。为此，c-AFM将被用来关联的相位和电流图像上采取的操作半燃料电池，并确定部分的电化学活性水的表面域。PI和他的团队还将成像纳米级域形态和连接性，作为（1）更准确地反映燃料电池运行的环境条件，如高温和低相对湿度，（2）膜类型和组成，以及（3）催化剂颗粒与离子通道的接近度的函数。 这些实验的结果将被用于获得PEM燃料电池中离子电导的基本理解，并为下一代膜材料的开发提供灵感和见解。以高于内燃机的效率生产电力的可能性，以及环境友好的副产品，使燃料电池成为替代能源和可持续发展领域的重要参与者，特别是如果反应物来源于可再生资源。 从事该项目的学生将接触到这种替代电源，帮助优化生产隔膜的工业过程，并为发现新的膜材料提供重要的见解。 此外，学生将接受最先进的扫描探针显微镜和纳米表征技术的培训。 由这笔赠款（包括PI）支持的研究人员也将积极推广到圣巴巴拉地区的K-12学校。 从事该项目的研究人员还计划开发一个运行燃料电池的演示，该演示将包括在UCSB化学系目前活跃的推广计划中。 此外，他们还将每年三次访问圣巴巴拉和文图拉县的高中，讨论他们的研究及其影响，并促进科学教育。

With support from the Chemical Measurement and Imaging Program in the Division of Chemistry, and co-funding from the Polymers Program in the Division of Materials Research, Professor Steven Buratto and his group at University of California-Santa Barbara are utilizing conductive atomic force microscopy (c-AFM) to image ion conductance and pore connectivity in proton exchange membranes (PEM) used in PEM fuel cells on a nanometer length scale and at the level of a single pore channel. PEM fuel cells, which convert chemical energy into electricity using an electrochemical cell, can be used as efficient power sources, offering high power density and low environmental impact. Critical to fuel cell performance is the polymer electrolyte membrane, which is an efficient proton conductor but an electric insulator. A detailed understanding of proton conduction, in terms of the size and distribution of the chemical domains responsible for transport, is crucial to both a complete understanding of fuel cell performance and a systematic approach to improving the performance. To this end, c-AFM will be used to correlate phase and current images taken on an operating half fuel cell and determine the fraction of electrochemically-active aqueous surface domains. The PI and his group will also image the nanoscale domain morphology and connectivity as a function of (1) the environmental conditions that more accurately reflect those of an operating fuel cell such as high temperature and low relative humidity, (2) the membrane type and composition, and (3) the proximity of the catalyst particles to the ion channels. The results of these experiments will be used to gain a fundamental understanding of ion conductance in PEM fuel cells and provide inspiration and insight into the development of the next-generation membranes materials.The possibility of producing power with efficiency greater than internal combustion engines, and with environmentally benign byproducts, makes fuel cells an important player in the field of alternative energy and sustainability, especially if the reactants are derived from renewable resources. Students working on this project will be exposed to this alternative source of power, help optimize industrial processes that produce polyelectrolyte membranes, and provide important insight into the discovery of new membrane materials. In addition, students will be trained in state-of-the-art scanned probe microscopy and nano-characterization techniques. Researchers supported by this grant (including PIs) will also be active in outreach to K-12 schools in the Santa Barbara area. Researchers working on this project also plan to develop a demonstration of an operating fuel cell that will be included in the currently active outreach program in the chemistry department here at UCSB. In addition, they will visit high schools in the Santa Barbara and Ventura Counties three times per year to discuss their research and its impact as well as to promote science education.