Synthesis of a hierarchical SiO2/Au/CeO2 rod-like nanostructure for high catalytic activity and recyclability†
Abstract
Uniform hierarchical SiO2/Au/CeO2 rod-like nanostructures were successfully fabricated by combining three individual synthesis steps, in which sub-5 nm gold nanoparticles (Au NPs) were coated with a mesoporous CeO2 shell. This method involves preparation of rod-like silica particles, deposition of Au NPs through a self-assembly procedure and then sequential deposition of CeO2 layers. To investigate the catalytic structure, the obtained sample was characterized by several techniques, including transmission electron microscopy (TEM), X-ray powder diffraction (XRD), N2 adsorption–desorption isotherms (BET), and UV-vis diffuse reflection spectroscopy. It was found that SiO2/Au/CeO2 possessed an integral core shell structure including encapsulated Au NPs as core and mesoporous CeO2 as shell. Meantime, the inner silica plays an important role in the morphology control and improvement of the catalyst mechanical strength. The sample shows unique features such as uniform rod-like morphology, well dispersed Au NPs, and large specific surface area. The results of reaction performance indicate that the synthesized SiO2/Au/CeO2 catalysts exhibit significantly enhanced catalytic activity. Moreover, the catalytic activity of our as-prepared nanocomposite catalysts was well maintained even after 8 repeated cycles. It is clear that the core–shell composites can be used as effective nanoreactors with superior catalytic activity and recyclability due to their unique structural features.