基于PPy-Nafion有序结构的超低铂载量Pt薄膜一体化电极研究

Membrane electrode assembly (MEA) is the core component of fuel cell. Its material and structure directly affect the performance, life and cost of fuel cell. At present, the traditional electrode shows up the characteristics of disordered structure, low Pt utilization and poor stability. In the traditional electrode structure, the catalyst and proton conductor are disordered, which is not conducive to the construction of three-phase interface. The disordered structure cannot form continuous through-hole channel, which is not conducive to the transfer of reaction gas and the discharge of generated water. This project intends to take the ordered array of conductive polymer PPy doped with proton conductor Nafion as the carrier, introduce the concept of Pt monatomic layer into the ordered electrode, and use underpotential deposition technology with replacement reaction to prepare the integrated electrode of continuous Pt thin film with ultra-low Pt loading, so as to achieve the maximum Pt utilization and avoid the instability of particle catalyst. In addition to the ordered carrier, the electrode structure is coupled with ordered gas-liquid transport channel, ordered electron and proton transport channel. Based on the study of material preparation, this project will explore the formation mechanism of ordered nanoarrays, in combination with study of mathematical model, so as to provide theoretical guidance for constructing ordered electrodes with appropriate size, reasonable composition and excellent structure. Through the deep analysis of electrode materials and structures and the evaluation of catalytic properties, the internal relationship between the microstructure and the macroscopic properties of the MEA was revealed.

膜电极是燃料电池的核心组件，其材料与结构直接影响电池性能、寿命和成本。目前燃料电池电极存在结构无序、Pt利用率低、稳定性不佳等特点。传统结构电极中，催化剂与质子导体无序分布，不利于三相界面的构筑；无序结构不能形成连续贯通孔道，不利于反应气体传递和生成水的排出。本项目拟以导电聚合物PPy掺杂质子导体Nafion的有序化阵列为载体，将Pt单原子层概念引入有序化电极，利用欠电位沉积结合置换反应制备超低铂载量连续Pt薄膜一体化电极，实现最大Pt利用率同时避免颗粒催化剂不稳定。该电极结构除载体有序外，还同时耦合了气液传输通道、电子传输通道和质子传输通道有序。本项目将从材料制备入手，探究有序化纳米阵列的形成机制，结合数学模型研究，为构筑尺寸合适、成分合理、结构优异的有序化电极提供理论指导。通过对电极材料和结构的深入解析、催化性能的评价，揭示膜电极微观结构与宏观性能之间的内在联系。

膜电极是燃料电池的核心组件，其材料与结构直接影响电池性能。传统电极存在结构无序、Pt利用率低、稳定性不佳等问题，催化剂与质子导体无序分布，不利于三相界面的构筑，无序结构也不便形成连续贯通孔道，不利于反应气体传递和生成水的排出。本项目以导电聚合物PPy掺杂质子导体Nafion的有序化阵列为载体，同时作为质子与电子的有序传输通道，将Pt单原子层引入有序化电极，利用欠电位沉积结合置换反应制备超低铂一体化电极，实现Pt的高效利用。本项目研究了PPy-Nafion有序结构复合载体的电化学合成及生长机理，在炭纸和碳布载体表面制备出了有序纳米线阵列载体，实现了Nafion聚离子的掺杂，研究了不同条件对纳米线阵列成分结构的影响，提出了碳载体表面有序化纳米线阵列自催化形成机理。进行了有序化阵列载体表面Pt原子层催化剂的可控制备技术研究，掌握了纳米线表面Cu欠电位沉积特点，制备了基于复合有序载体、不同Pt原子层厚度的Pt薄膜一体化电极，将Pt单原子层概念应用于有序电极，提供了超低铂电极制备新方法，对制备的一体化Pt薄膜电极进行了电极结构、表面亲疏水性及电化学性能评价。在实验基础上，以有序化电极为对象，初步建立了耦合传质和电化学反应的有序化电极模型，并将模型计算结果与实验测试结果进行了对比验证。研究了催化层厚度及纳米线阵列间隙等结构参数对电池性能的影响，分析了有序化电极中的气液传质规律，为超高Pt利用率有序化电极的发展提供了科学依据和理论指导。