Facile Preparation of Mn+-Doped (M = Cu, Co, Ni, Mn) Hierarchically Mesoporous CeO2 Nanoparticles with Enhanced Catalytic Activity for CO Oxidation

A series of transition-metal-doped (Cu, Co, Ni, Mn) hierarchically mesoporous CeO2 nanoparticles have been fabricated through a simple solvothermal strategy. The effect of these doping metals on the morphology and the phase transformation of the Ce(HCOO)(3) precursor was investigated. The specific order in which the doping metal cations (except Cu2+) are added during the synthesis process has a remarkable influence on the precursor morphology. By introducing these different metal cations, the doping composition can be adjusted freely. The XRD, Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS) results show the high homogeneity of the doped ceria and demonstrate that the transition metal cations have been incorporated into the CeO2 lattice. All of the doped ceria nanoparticles, especially the Cu2+-doped ceria product, exhibit improved reduction behavior and enhanced CO conversion performance.