Copper doped ceria nanospheres: surface defects promoted catalytic activity and a versatile approach

In this paper, Cu2+ doped ceria nanospheres were produced from a one-step hydrothermal synthesis. The products were characterized in detail at the structural and electronic level by X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy, high-resolution transmission electron microscopy (HRTEM) and X-ray photoelectron spectroscopy (XPS). XRD results revealed that the doped ceria was free of other crystallographic phases, such as CeOHCO3, CuO or Cu2O. By introducing various reactant molar ratios of Cu : Ce, the composition can be freely manipulated. The H2-TPR measurement shows the improved reduction behaviour of the doped ceria samples prepared by us. A preliminary CO catalytic oxidation experiment indicated that the Cu2+ doped ceria samples showed strikingly higher catalytic activity, due to the intrinsic surface defects of the samples. In addition ceria doped with other transition metal ions (M2+), such Co2+, Ni2+ and Mn2+, has also been successfully prepared. Considering this one-step synthesis as a versatile approach, it can be further extended to other binary metal oxide systems.