Morphology and Crystal-Plane Effects of Nanoscale Ceria on the Activity of CuO/CeO2 for NO Reduction by CO

The present work elucidated the morphology and crystal-plane effects of nanoscale ceria on the activity of CuO/CeO2 catalysts toward NO reduction. CeO2 Nanopolyhedra were enclosed by (111) and (100) planes; the nanorods predominantly exposed (110) and (100) surfaces, and the nanocubes only showed the polar (100) planes. Moreover, the strongest interaction was between CuO and CeO2 rods, followed by CuO/CeO2 polyhedra, and the CuO/CeO2 cubes showed the least interaction. Importantly, Cu2+ ions could be incorporated into the pore and sur-face lattices by occupying the vacant sites in the nanostructure CeO2 rods. Partial copper oxide species were segregated on the surface of CeO2 cubes with larger particle sizes. As a result, the site geometry and coordination environment of Cu2+ ions were different on the (111), (110), and (100) surfaces of CeO2. This surface structure effect in turn led to a higher surface reducibility, activity and N-2 selectivity of CuO/CeO2 nanorods for NO reduction at low temperatures (below 250 degrees C); the polyhedra and cubes were less active.