New composite DMFC anode with PEDOT as mixed conductor and catalyst support

直接甲醇燃料电池(DMFC)作为电化学电源因其系统设计简单、工作温度低、燃料储存和供应方便等优点而备受关注。DMFC的主要局限性与低功率密度有关，这是阳极反应动力学不佳、反应中间体对催化剂中毒和甲醇交叉的结果。研究工作必须解决阳极催化剂结构和离子交换膜的改进问题。本项目旨在以导电聚合物PEDOT(聚(3，4-乙烯-二氧基噻吩基))为催化剂载体，结合一种新型的降低甲醇渗透率的质子交换膜(PEM*)，开发一种新型膜阳极组件PEM*/PEDOT/CAT。指定的催化剂(CAT)为铂、铂-Ru。这一新系统将与传统的铂/碳阴极一起用于制造膜电极组件(MEA)，以便在单电池实验中进行测试。在渗透汽化膜的基础上，开发了一种高质子电导率、低甲醇渗透率的新型膜(PEM~*)。PEDOT作为电子/离子混合导体的应用有望改善电荷转移动力学以及质子和电子在阳极结构中的传输，从而更好地利用贵金属催化剂。离子交换膜和导电聚合物PEDOT之间的直接接触将通过在DFG优先计划1060中为聚吡咯开发的特殊聚合技术来实现。PEM*/PEDOT/CAT组件将通过电化学方法(CV、EIS、瞬变技术)、表面分析(扫描电子显微镜、能谱分析、透射电子显微镜、X射线衍射仪)和光谱分析(IR、UV/Vis)进行表征。采用新的阳极结构和传统的铂/碳阴极的MEA将通过丝网印刷来生产。在单个电池单元中的测试将用于确定电流-电压特性、功率密度、甲醇周转率、反应产物和甲醇交叉。对电极和整个电池中发生的传输过程和反应进行建模和模拟将有助于了解性能，从而有助于新MEA的实验开发。

The direct methanol fuel cell (DMFC) as electrochemical power source has attracted considerable attention due to its simple system design, low operating temperature, and convenient fuel storage and supply. Major limitations of the DMFC are related to the low power density, which is a consequence of poor kinetics of the anode reaction, poisoning of the catalyst by reaction intermediates, and methanol crossover. Research efforts have to address improvements of the anode catalyst structure and the ion-exchanger membrane. This project aims at the development of a new type of membrane anode assembly PEM*/PEDOT/CAT based on the conducting polymer PEDOT (Poly(3,4ethylene-dioxythiophene)) as catalyst support in combination with a new type of proton-exchange membrane (PEM*) with reduced methanol permeability. The designated catalyst (CAT) is Pt, Pt-Ru. This new system will be used with a conventional Pt/C cathode to manufacture membrane electrode assemblies (MEAs) to be tested in single cell experiments. Based on pervaporation membranes for separating water from alcohol, a new type of membrane (PEM*) with high proton conductivity and low methanol permeability is going to be developed. The application of PEDOT as mixed electronic/ionic conductor is expected to improve the charge transfer kinetics and the transport of protons and electrons within the anode structure leading to a better utilisation of the noble metal catalyst. Direct contact between the ion-exchanger membrane and the conducting polymer PEDOT will be achieved by a special polymerisation technique that has been developed for polypyrrole within the DFG priority programme 1060. The PEM*/PEDOT/CAT assembly will be characterised by electrochemical methods (CV, EIS, transient techniques), surface analysis (SEM, EDAX, TEM, XRD), and spectroscopy (IR, UV/Vis). MEAs employing the new anode structure and a conventional Pt/C cathode will be produced by screen printing. Tests in a single cell unit will serve to determine the current-voltage characteristics, the power density, the methanol turnover, the reaction products, and the methanol crossover. Modelling and simulation of transport processes and reactions taking place in the electrodes and in the complete cell will help to understand the performance and hence aid the experimental development of the new MEA.