Synthesis and Characterization of Colloidal-Supported Metal Nanoparticles as Potential Intermediate Nanocatalysts

Abstract

We report the synthesis of a new type of intermediate nanocatalyst material that we term as colloidal-supported metal nanoparticles (CSMNs). The CSMNs that we have synthesized consist of palladium nanoparticles covalently attached to functionalized silica colloids. The synthesis process involves four steps, which include the synthesis of the silica colloids, synthesis of the palladium nanoparticles, functionalization of the silica colloids with 3-mercaptopropyl trimethoxysilane (MPTMS) or 3-aminopropyl triethoxysilane (APTES), and covalent attachment of the palladium nanoparticles onto the functionalized silica colloids. We have characterized the size of the silica colloids and palladium nanoparticles by using transmission electron microscopy (TEM). In addition, we have characterized the attachment of the palladium nanoparticles onto the two types of functionalized silica colloids by using TEM as well as energy dispersive spectroscopy (EDS). In the case of the CSMNs prepared by using the silica colloids functionalized with MPTMS, we observed that there is a significant amount of additional deposits between each of the functionalized silica colloids. This type of additional deposits is significantly diminished in the case of the CSMNs prepared by using silica colloids functionalized with APTES. We have conducted some initial studies to determine at what stage the additional deposits occur and discuss potential sources that give rise to this phenomenon. We have also conducted initial kinetics study and assessment of the stability of the CSMNs after the catalytic process.