Preparation and Characterisation of Atomic Metals in Polyaniline

本项目旨在制备无配体贵金属簇，其中原子数精确控制在1到7之间。这是通过电化学控制的原子-原子沉积在共轭聚合物聚苯胺的基质中实现的。这种结构被证明具有有趣的催化性质。在Au的特殊情况下，在醇的催化氧化中证明了与原子数有关的特征性奇偶行为。它遵循了理论预测的电子结构计算趋势。主要的焦点将是金、钯的原子团簇及其混合物（原子合金）在玻璃碳衬底上的电化学生长聚苯胺中的生长。将通过电化学阻抗谱、循环伏安法、FTIR、XPS、RBS和电子显微镜对样品进行彻底的物理和化学表征。最先进的技术被用于对贵金属团簇的存在进行原子成像。这些包括分析高分辨率扫描透射电子显微镜以及三维原子探针。此外，x射线吸收被应用于研究团簇的化学环境作为原子序数的函数，而远红外红外将试图探测原子团簇的大小和形状的特定指纹。此外，还测试了这些原子金属电极对氧还原反应的催化性能，以及对甲醇和乙醇氧化的催化性能，以研究它们作为燃料电池催化剂的潜力。原子金属簇的使用可能导致单位面积所需贵金属负载的显著减少。

This project aims for the preparation of ligand-free noble metal clusters, where the number of atoms is precisely controlled from 1 to 7. This is achieved by an electrochemically controlled atom-by-atom deposition in a matrix of the conjugated polymer polyaniline. Such structures were demonstrated to have interesting catalytic properties. In the specific case of Au, a characteristic odd-even behaviour with respect to the number of atoms was demonstrated on the catalytic oxidation of alcohols before. It follows the theoretically predicted trend in electronic structure calculations. The main focus will be on the growth of atomic clusters of Au, Pd and mixtures (atomic alloys) thereof in electrochemically grown polyaniline supported on glassy carbon substrates. A thorough physical and chemical characterization will be carried out on the samples by electrochemical impedance spectroscopy, cyclic voltammetry, FTIR, XPS, RBS and electron microscopy. State-of-the-art advanced techniques are used in cooperation to atomically image the presence of the noble metal clusters. These include analytical high resolution scanning transmission electron microscopy as well as three-dimensional atomprobe. Furthermore, X-ray absorption is applied to study the chemical environment of the clusters as a function of atomic numbers, whereas far infrared FTIR will be attempted to probe the atomic clusters’ size- and shape-specific fingerprint. Furthermore, the catalytic performance of these atomic metal electrodes is tested for the oxygen reduction reaction as well as for methanol and ethanol oxidation to study their potential as a fuel cell catalyst. The use of atomic metal clusters may lead to a significant reduction of the needed noble metal load per unit area.