[Zurück]

C. Garcia Yago, N. Barrabés-Rabanal, G. Rupprechter:
"Aun(SR)m heterogeneous catalysis: Pd doping effect in oxidation reactions";
Poster: 6th International Symposium on Monolayer Protected Clusters (ISMPC 19), Xiamen (China); 23.09.2019 - 26.09.2019.

Metal nanoparticles supported on oxides are often limited in activity, selectivity or durability, due to variations in metal particle size, surface structure and bonding to the support. Thiolate-protected Au nanoclusters supported on metal oxides have shown enhanced catalytic activity in several reaction processes, both in liquid phase and gas phase. Atomically designed metal clusters offer the possibility to design well-defined and truly homogeneous surfaces, leading to optimal catalysts for reaction mechanism studies. However, understanding the stability of the cluster structure and type of interaction with the support under reaction conditions is crucial for their catalytic application [2] In the present work, the stability of Au144 and Au25 clusters, supported on TiO2 and on SiO2, was examined upon thermal air pretreatment and, for the first time, upon liquid phase oxidation reaction [3]. Significant support influence (TiO2 vs. SiO2) and size dependence (Au144 vs. Au25) was revealed by diverse spectroscopic technics as synchrotron x-ray spectroscopy (XAS), diffuse reflectance spectroscopy and scanning transmission electron microscopy. Operando infrared spectroscopy revealed fundamental differences in reaction pathways and HERFD-XAS measurements pointed out a pronounced cluster structure modification towards bulk gold during the reaction.