Ligand-free gold nanoclusters confined in mesoporous silica nanoparticles for styrene epoxidation

Abstract

We present a novel approach to produce gold nanoclusters (Au NCs) in the pores of mesoporous silica nanoparticles (MSN) by sequential and controlled addition of metal ions and reducing agents. The impregnation technique was followed to confine Au NCs inside the pores of MSN without adding external ligands or stabilizing agents. TEM images show uniform distribution of monodisperse NCs over the entire MSN. Since the NCs are grown in situ in MSN pores, additional support and high temperature calcination are not required to use them as catalysts. The use of MSN /Au NCs as a catalyst for the epoxidation of styrene resulted in very high conversion of styrene and high selectivity towards styrene epoxide. The catalysis reaction was environmentally friendly due to solvent free approach and low reaction temperature (60-80oC). Our synthetic approach can be extended to other metal NCs offering a wide range of applications.