CeO2 hollow nanospheres synthesized by a one pot template-free hydrothermal method and their application as catalyst support

Abstract

Uniform ceria hollow nanospheres composed of ceria nanocrystals have been synthesized via a simple one-step hydrothermal method without using any template. Afterwards, these hollow materials were used as support to prepare the Au/CeO₂ catalyst for the reduction of 4-nitrophenol (4-NP). It was found that the obtained porous CeO₂ hollow nanospheres were morphologically uniform, with an average diameter of 210 nm and high specific surface area of 167 m² g⁻¹. According to the basis of a time-dependent experiment, a self-assembly process coupled with an Ostwald ripening mechanism was proposed to explain the evolution of CeO₂ hollow nanospheres. In comparison with the commercial CeO₂ powder supported sample, the synthesized hollow Au/CeO₂ nanospheres catalyst exhibited significantly enhanced catalytic activity. In addition, the results of cyclic stability of the catalyst indicated that similar catalytic performance without visible reduction could be found after 7 repeated cycles. As for this catalyst system, the unique porosity structures of the support, uniform distribution of metallic particles together with the high thermal stability of Au NPs were all responsible for the improved reaction properties.