A comparative study of CO oxidation over Cu-O-Ce solid solutions and CuO/CeO2 nanorods catalysts

The distribution of copper species (on the surface or in the bulk of CeO2 support) and the interfacial interactions between CuO and CeO2 are critical in understanding the synergistic effect on the catalytic activity of CeO2 supported CuO catalysts. In this report, Cu-O-Ce solid solutions and CuO impregnated on CeO2 nanorods catalysts (CuO/CeO2) with various compositions were prepared using thermal decomposition and hydrothermal methods, to understand the distribution effect of copper species on low temperature CO oxidation. The incorporation of copper ions into CeO2 lattice in both types of catalysts was confirmed by X-ray diffraction (XRD), Raman spectroscopy, and hydrogen temperature programmed reduction (H2-TPR) analysis, indicating a strong CuO-CeO2 interfacial interaction and formation of oxygen vacancies which compensates the charge difference between copper (I/II) and cerium (III/IV) ions. A series of temperature programmed reduction-temperature programmed oxidation (TPR-TPO) thermal cycling studies were conducted to understand the interactions between three assigned copper species (α, β, and γ) with CeO2 support and the corresponding catalytic performance of the catalysts. In addition, an improved low temperature catalytic performance for the CuO/CeO2 nanorods catalysts was observed, which was attributed to stronger interactions between copper species and CeO2 nanorods enriched with surface defects (steps and voids etc.).