An Environmentally Friendly Approach for the Synthesis of Au Nanoparticles Supported Mesoporous Silica for Catalytic Applications

Abstract

Mesoporous silica has received much attention as an attractive support material for metal nanoparticles (NPs) with good dispersion and exceptional stability for various catalytic reactions. However, the lack of synthetic protocols to controlled synthesis of mesoporous silica with high surface area and ideal pore size for supporting metal NPs significantly reduces the catalytic performance and stability of the catalysts. This work reports a facile synthetic route to prepare mesoporous silica-supported Au NPs (Au/SiO2) for efficient catalytic reduction of 4-nitrophenol. An environmentally friendly synthetic route was exploited to prepare mesoporous silica using deep eutectic solvent (DES) derived from choline chloride/urea as an efficient solvent and template in solvothermal reaction. The mesoporous silica was first functionalized with –NH2 groups, and subsequently, Au NPs with an average size of 10 nm were deposited onto the mesoporous silica matrix. Owing to the strong interaction of supported Au NPs with the mesoporous silica support, the resultant composite exhibited excellent catalytic performance towards the reduction of 4-NP to 4-aminophenol with a rate constant of Kapp= 3.04 x10-1 min-1 and exceptionally high stability compared to bare mesoporous silica catalyst. The current green approach to fabricating mesoporous silica and Au/SiO2 catalysts holds great promise since it is a much cheaper and environmentally friendly method for large-scale fabrication of other supported catalysts for different catalytic reactions.