Preparation of TiO2–ZrO2/Au/CeO2 hollow sandwich-like nanostructures for excellent catalytic activity and thermal stability

Abstract

This work reports a novel type of sandwich-like hollow Au-based nanocatalyst, including a TiO₂–ZrO₂ shell, a hollow CeO₂ core and Au nanoparticles of 2–5 nm. Uniform crystal ceria hollow nanostructures were synthesized using a simple one-step hydrothermal method without a template. Then binary TiO₂–ZrO₂ coated Au nanocatalysts were prepared via a facile bottom-up synthesis method. The structural features of the catalysts were characterized by several techniques, including SEM, TEM, EDX, FTIR, BET, XRD, UV-vis and XPS analyses. Using the reduction of 4-nitrophenol by NaBH₄ as a model reaction, the TiO₂–ZrO₂/Au/CeO₂ microspheres showed a superior catalytic activity and thermal stability compared with a pure TiO₂ or ZrO₂ layer. In addition, TiO₂–ZrO₂/Au/CeO₂ microspheres calcined at 700 °C presented the highest thermal stability and reactivity. These comparative results were mainly attributed to the synergistic effect among the mixed oxide, hollow CeO₂ core and Au NPs and the sandwich-like structure. As a consequence, this unique nanocatalyst will open a promising route for the fabrication of hollow binary-metal-oxide materials for future research and has great potential for other applications.