Facile and green fabrication of efficient Au nanoparticles catalysts using plant extract via a mesoporous silica-assisted strategy

Abstract

In this study, highly dispersed Au nanoparticles supported on mesoporous silica were successfully prepared using avocado leaf extract. Due to the in-situ growth of the Au nanoparticles within the confined geometric space of the silica pores these nanoparticles are on average ≈7.7 nm in diameter, much smaller than those prepared without mesoporous silica (≈20 nm), and within the critical size range required for Au catalysts (<10 nm). The reduction and stabilization of the Au nanoparticles within the silica pores is enabled by aqueous biomolecules from the plant extract. The immobilization of the Au nanoparticles on the silica facilitates their separation and purification from the complex plant extract solution. Excellent catalytic performance and reusability is demonstrated by the reduction of 4-nitrophenol. This approach offers a facile, low-cost and environmentally benign method for synthesis of advanced Au-based catalysts from readily available silica materials and Au complexes with potential application in areas such as drug delivery and chemical/bio-sensing. The design concept can be extended to green synthesis of other metal or metal oxide compositions.