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.