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Enhanced Catalytic Performance of (CuO)x/Ce0.9Cu0.1O2 Nanospheres: Combined Contribution of the Synergistic Effect and Surface Defects

Hongxiao Yang,Yue Pan,Yucong Xu,Yanzhao Yang,Guoxin Sun

Graphical Stuck in the middle : A series of copper-modified ceria catalysts has been synthesized in a facile way. (CuO) x /Ce 0.9 Cu 0.1 O 2 showed excellent catalytic activity in CO low-temperature oxidation. The combined contribution of the synergistic effect and surface defects facilitates the CO oxidation at the interface between ceria and copper species (see scheme). Copper-modified ceria catalysts, (CuO) x /Ce 0.9 Cu 0.1 O 2 nanospheres, for low-temperature CO oxidation were fabricated simply by using the hydrothermal synthesis of Cu-doped CeO 2 (Ce 0.9 Cu 0.1 O 2 ) nanospheres followed by deposition of CuO over Ce 0.9 Cu 0.1 O 2 . The X-ray diffraction and electron spectroscopy characterizations demonstrated that the as-prepared nanospheres were composed of cubic CeO 2 and monoclinic CuO with a typical diameter of around 70 nm. Moreover, the X-ray photoelectron spectroscopy (XPS) analysis illustrated the coexistence of Ce 4+ /Ce 3+ and Cu 2+ /Cu + redox couples in (CuO) x /Ce 0.9 Cu 0.1 O 2 and H 2 temperature-programmed reduction (TPR) measurements indicated the excellent reduction behavior of the catalyst. The Raman spectra illustrated the oxygen vacancy in (CuO) 0.3 /Ce 0.9 Cu 0.1 O 2 , and diffuse-reflectance infrared Fourier transform spectroscopy (DRIFTS) demonstrated the stable existence of Cu + species during CO oxidation. The (CuO) x /Ce 0.9 Cu 0.1 O 2 nanospheres showed excellent catalytic activity toward CO oxidation in normal feed gas (volume ratio of CO/O 2 /N 2 =1:10:89) at ambient temperature. Catalytic tests revealed that the proportion of CuO in the final product has a strong influence on the resultant catalytic activities. The (CuO) x /Ce 0.9 Cu 0.1 O 2 nanospheres hold great application potential as new catalysts for CO oxidation.