Novel Synthesis of Gold Nanoparticles Supported on Alkyne-Functionalized Nanosilica

A novel, convenient method for the preparation of gold nanoparticles supported on alkyne-functionalized nanosilica is presented. Silica nanoparticles functionalized with alkynyl carbamate moieties (SiO2@Yne) were synthetized by co-condensation of the di-functional organosilane [3-(2-propynylcarbamate)propyl]triethoxysilane (PPTEOS) with tetraethoxysilane (TEOS) in alkaline medium. The alkynyl-carbamate functionalities present on silica are able to capture the gold precursor HAuCl4, spontaneously reduce it, and stabilize the resulting supported AuNPs, having an average size of ca. 11 nm. The prepared Au-SiO2@Yne was thoroughly analyzed by X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), transmission electron microscopy (TEM), atomic absorption spectroscopy (AAS), FT-IR and UV-Vis spectroscopy. The catalytic activity of Au-SiO2@Yne was investigated for the reduction of 4-nitrophenol to 4-aminophenol by NaBH4 and kinetic constants k in the order of magnitude of about 10-2 s-1 were found.