Organosilane-Assisted Transformation from Core-Shell to Yolk-Shell Nanocomposites

In this paper, we present the synthesis of yolk-shell nanocomposites (NCs) with moveable cores (Fe3O4, Au nanoparticles (NPs)) and functionalized organosilica mesoporous shells by an organosilane-assisted etching approach for the first time. This synthesis method is facile, general, and rapid. By adding organosilanes such as 1, 2-bis(trimethoxysilyl)ethane (BTME) and 1,4-bis(triethoxysilyl)benzene (BTEB) into the synthetic medium of NPs@silica (Fe3O4 and Au NPs) core-shell NCs, the organosilica species deposit on the surface of the core-shell NCs, while the initial silica shells can be subsequently dissolved to form the yolk-shell NCs. The formation of such yolk-shell NCs can be reasonably explained by a novel organosilane-assisted etching mechanism based on the results of FT-IR and Si-29 NMR spectroscopy. The yolk-shell NCs with Au cores exhibit much higher catalytic activity than the Au@silica core-shell NCs for the catalytic reduction of o-nitroaniline, probably due to the higher accessibility of the Au active sites in the yolk-shell NCs.