Synthesis of confined Ag nanowires within mesoporous silica via double solvent technique and their catalytic properties

Ag nanowires within the channels of mesoporous silica have been successfully synthesized via a double solvent technique, in which n-hexane is used as a hydrophobic solvent to disperse mesoporous silica and an AgNO3 aqueous solution is used as a hydrophilic solvent to fill mesochannels. The morphology of the obtained Ag (nanowires, nanoparticles or nanorods) can be controlled by adjusting the concentration of AgNO3 solution and the template pore size. HRTEM images demonstrate extensive Ag nanowires with several to tens of hundreds nanometers in length are deposited along the long axis of mesochannels when the atomic AgNO3/Si ratio is 0.090. When the atomic AgNO3/Si ratio is 0.068 or 0.11, there is a combination of Ag nanoparticles and nanowires; nanoparticles are mainly formed when the atomic AgNO3/Si ratio is higher than 0.14. Further, the catalytic results of the oxidation of styrene show that styrene oxide and benzaldehyde are the main products of the reaction, and the morphology and diversity of Ag in Ag/mesoporous silica composites have an effect on the conversion of styrene and selectivity of styrene oxide. (C) 2011 Elsevier Inc. All rights reserved.