Synthesis and Characterization of Functionalized Platinum Nanoparticles

Abstract

The elaboration and characterization of platinum nanoparticles functionalized with 4-mercaptoaniline is reported. An important point of the synthesis scheme is the use of hexylamine as intermediate labile capping agent. The size and structure of the platinum inner core have been analyzed by X-ray diffraction and TEM microscopy. It is found to be crystalline with a fcc structure and a cell parameter of 0.392 nm very close to the bulk value. The size dispersity is low with an average diameter of ca. 1.5 nm. A well-defined interparticle distance of ca. 3.2 nm is found, corresponding to an organic overlayer thickness of 0.9 nm in good agreement with the estimated molecule length. A rough estimation of the surface per absorbed molecule yields a value of ca. 0.14 nm2, pointing to a dense molecular packing. However, IR spectroscopy reveals a very slow degradation process of the organic overlayer, eventually resulting in the formation of sulfate ions onto the platinum surface. A promising perspective is the use of the amine end groups for subsequent overgrafting of the nanoparticles.