Projects

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.