Facile one-step synthesis of porous ceria hollow nanospheres for low temperature CO oxidation

Abstract

Herein, porous ceria (CeO2) hollow nanospheres composed of small nanoparticles have been controllably prepared through a simple one-step solvothermal reaction without using any hard-template. The products were characterized by X-ray powder diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), thermogravimetric analysis (TGA), fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM) and N2 adsorption/desorption analysis. It was found that the porous CeO2 hollow nanospheres composed of small nanoparticles with an average diameter of 3nm have a uniform size of 135nm and a high specific surface area of 145m2/g. A self-assembly process coupled with an Ostwald ripening mechanism for the hollow structures formation was proposed based on a series of time-dependent HRTEM observations. The catalytic performance of porous CeO2 hollow nanospheres and the Au/CeO2 composite catalyst for CO oxidation were also tested. The results indicate that these porous CeO2 hollow nanospheres are excellent supports for Au nanoparticles, the CO conversion by catalysis of Au/CeO2-A composite catalyst is 92% at ambient temperature. More importantly, the CO conversion could still be reached to 91% after the catalyst had been continuously used for 20h in CO oxidation at room temperature, indicating that the Au/CeO2-A catalyst had a high catalytic activity and high durability.