基于SURMOF制备三维有序多孔聚苯胺Pt阵列电极及其氧还原反应动力学性能研究

The performance of the fuel cell is constrained by the kinetic rate of oxygen reduction in membrane electrode assembly (MEA), and the Pt catalyst plays a decisive role in the reaction rate. Preparation of ordered array electrode is an effective way to improve Pt oxygen reduction activity. In this project, an ordered porous polyaniline film will be prepared by electro-polymerization method using metal organic framework as a template. And then, the Pt ordered array electrode was prepared on the ordered porous polyaniline by electrochemical deposition method. This material is not only inherited of the high porosity, high specific surface area, order and overall morphology from metal organic framework template, but also has show excellent conductivity and acid solution stability. At the same time, the kinetic equation of the ordered array electrode's reaction process is calculated by Foucault theorem and Buttler-Volmer equation. The state of the Pt atom and nanoparticle in the polyaniline film hole is calculated by density functional theory (DFT). The relationship between the structural characteristic parameters of the ordered array electrode and the electrical output performance is studied, and it is used to reveal the influence of catalytic activity of ORR. The theoretical results were verified by electrochemical test and optimize its structural characteristic parameters (such as electrode thickness, porosity, pore size and so on). This work is provides a new idea for the development of the next generation ordered array electrode.

燃料电池的性能受到膜电极中氧还原反应动力学速率制约，而Pt催化剂对反应速率起决定性的作用。制备有序阵列电极是提高Pt氧还原反应活性的一种有效途径。本项目将采用金属有机框架薄膜为模板通过电聚合法制备有序多孔聚苯胺薄膜，在此基础上进一步通过电化学沉积法在聚苯胺薄膜上制备出Pt有序阵列电极。这种有序电极材料不但继承了金属有机框架薄膜模板的高孔隙率、高比表面积、有序性和整体形貌，而且具有优良的导电性和酸性溶液稳定性。同时，以菲克定理和Buttler-Volmer方程为基础推导有序阵列电极的反应过程动力学方程，通过密度泛函理论（DFT）计算模拟Pt原子及纳米颗粒在聚苯胺薄膜孔中的状态并揭示其对ORR催化活性的影响，研究有序阵列电极的结构特征参数与电输出性能的关系。最后，通过电化学测试验证理论结果，优化其结构特征参数（如电极厚度、孔隙率、孔径等），为下一代有序阵列电极开发提供新的思路。

燃料电池的性能受到膜电极中氧还原反应动力学速率制约，而Pt催化剂对反应速率起决定性的作用。制备有序阵列电极是提高Pt氧还原反应活性的一种有效途径。因此，本项目首先基于有效扩散系数、努森扩散和自由扩散等电极内氧传质阻力相关主要参数计算结果，构建了有序膜电极氧气传输动力模型，研究了该模型的氧气分布、氧传质阻力等情况，同时通过密度泛函理论（DFT）计算模拟Pt原子及纳米颗粒在聚苯胺薄膜孔中的状态。结果表明本课题需要制备有序阵列电极结构为间距100nm的柱状阵列，柱子直径为10-100nm，Pt催化剂需要加载到SURMOF表面形成颗粒状分布才能得到最优的氧还原反应效果。同时，为了验证氧传质阻力理论计算数值，本项目成功开发了气态电极测试装置，并测试有序电极氧传质阻力。测试结果发现孔径小于100nm情况下，其氧传质阻力比传统商业Pt/C电极大20倍左右，此结果与理论计算结果相符合，验证了有序阵列电极结构合理性。另外，本项目根据项目需求开发了磁控溅射载铂技术。通过控制溅射参数，成功在基底材料表面沉积了Pt纳米颗粒，在Pt载量为0.08mg/cm2时，其电池性能达到了0.90W/cm2@2A，此结果为有序阵列电极表面载铂提供有效方法。最后，本项目也完成SURPANI基体和Pt有序阵列电极的制备及其结构和性能表征相关工作。本项目成功制备出Cu3(BTC)2型SURMOF，同时通过电聚合反应制备有序聚苯胺阵列，XRD、SEM等测试结果均证明（002）晶面定向生长的SURMOF被成功制备，电聚合酸洗后CV测试证明聚苯胺已成功聚合，电池性能测试表明SURPANI有序阵列电极开路电压约为0.91V，电池性能达到了0.6V@0.7Acm-2。本项目制备的有序阵列电极，不但继承了金属有机框架薄膜模板的高孔隙率、高比表面积、有序性和整体形貌，而且具有优良的导电性和酸性溶液稳定性，为下一代有序阵列电极开发提供新的思路。