Gold nanoparticles grown on a hydrophobic and texturally tunable PDMS-like framework

Abstract

Mesoporous silicas are among the most suitable high-surface area solids to support small-sized metal clusters and nanoparticles. Unfortunately, the instability of silica in water constitutes a serious impediment for its widespread use and large implementation as a catalytic support for fine chemical synthesis and for biomass upgrading in the context of biorefineries. While end cupping silanols provides a way for delaying framework degradation, further investigations are needed to design more robust, water-resistant supports. Prompted by the success of polydimethylsiloxane (PDMS) in surface coating and water-repellent technologies, we herein explore the transformation of triethoxysilyl-functionalized polymethylethylsiloxane – a sol–gel analogue of PDMS – into a hydrophobic disordered mesoporous MCM-41-type siloxane framework. The concomitant addition of a soluble gold precursor during the mesophase formation followed by surfactant removal resulted in the entrapment and growth of gold nanoparticles inside. Thermally induced evolution of the PDMS-like siloxane framework was further investigated both under inert and open air atmospheres. Gold accessibility was ascertained during the transformation of nitrophenol, a harmful water pollutant, into aniline as a valuable amine-based precursor. Owing to the virtues of the PDMS-like framework for slowing down water and oxygen diffusion, the catalysts preserve their activity even after 18 months of storage under an open air atmosphere.