Facile Preparation of Well-Dispersed CeO₂–ZnO Composite Hollow Microspheres with Enhanced Catalytic Activity for CO Oxidation

In this article, well-dispersed CeO₂–ZnO composite hollow microspheres have been fabricated through a simple chemical reaction followed by annealing treatment. Amorphous zinc–cerium citrate hollow microspheres were first synthesized by dispersing zinc citrate hollow microspheres into cerium nitrate solution and then aging at room temperature for 1 h. By calcining the as-produced zinc–cerium citrate hollow microspheres at 500 °C for 2 h, CeO₂–ZnO composite hollow microspheres with homogeneous composition distribution could be harvested for the first time. The resulting CeO₂–ZnO composite hollow microspheres exhibit enhanced activity for CO oxidation compared with CeO₂ and ZnO, which is due to well-dispersed small CeO₂ particles on the surface of ZnO hollow microspheres and strong interaction between CeO₂ and ZnO. Moreover, when Au nanoparticles are deposited on the surface of the CeO₂–ZnO composite hollow microspheres, the full CO conversion temperature of the as-produced 1.0 wt % Au–CeO₂–ZnO composites reduces from 300 to 60 °C in comparison with CeO₂–ZnO composites. The significantly improved catalytic activity may be ascribed to the strong synergistic interplay between Au nanoparticles and CeO₂–ZnO composites.