Depth profile of alloying extent and composition in bimetallic nanoparticles investigated by in situ x-ray absorption spectroscopy

摘要

The authors report a general methodology for probing the depth profile of alloying extent and composition in bimetallic nanoparticles (NPs) by a combined in situ x-ray absorption spectroscopy (XAS) and electrochemical strategy. The XAS results of Pt-rich_(core)-Ru-rich_(shell) NPs during methanol electro-oxidation revealed that the alloying extent of Pt (J_(Pt)) and Ru (J_(Ru)) is higher in the core region compared to those in the shell region. An average decrease in the J_(Pt) and J_(Ru) is observed when the cluster undergoes reduction. By controlling the cluster oxidation degree it is possible to probe the depth profile of the alloying extent in bimetallic NPs.