A “Cluster-in-Cluster” Structure of the SiO2-Supported PtPd Clusters

The structures of SiO2-supported PtPd alloy clusters with the size of about 20 Å which were prepared from the PtPd colloid solutions were investigated by means of EXAFS. The phase shift and amplitude functions were derived from PtPd foils with the atomic ratio of 1:9, 1:1 and 9:1. The curve fitting analyses showed that the PtPd clusters were present in a “cluster-in-cluster” structure in which the homogeneous clusters were composed of several smaller clusters composed of the atoms of each metal.