Liquid phase catalytic application of nanoporous gold

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In this sub-project we will investigate the correlation between composition of npAu catalysts and their resulting catalytic performance for liquid phase oxidation reactions with O2. Modification of the surface by ad-metals such as Ag or Cu will be central means for reaching the objectives.The reactivity of nanoporous Au is a function of its surface composition. This unsupported catalyst with an extended and strongly curved Au surface offers unique possibilities in studying the influence of traces of ad-metals in a nanostructured host material. The presence of an ad-metal such as Ag or Cu will alter the electronic and chemical properties of the surface and by that will have a strong impact on the catalytic activity and selectivity of the material. From the first funding period we know that depending on its concentration the Ag can remain inside the ligaments in the form of clusters. At first we will further investigate the origin and dynamics of formation and dissolution of such clusters, aiming at a direct correlation between bulk and surface concentration of the Ag. Subsequently we will extend this study to Cu containing npAu in the aerobic oxidation of alcohols. Cu turned out to be more reactive but also is prone to oxidation and deactivation. Besides the mechanism of alcohol oxidation we will study possible reactive oxygen surface species such as O, OH and OOH as suggested by DFT calculations. We will study the epoxidation and oxidation of propene as a model reaction.