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

Abstract

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 surface 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 N2 selectivity of CuO/CeO2 nanorods for NO reduction at low temperatures (below 250 °C); the polyhedra and cubes were less active.

CO–PROX reactions on copper cerium oxide catalysts prepared by melt infiltration

“…This band has earlier been assigned to Cu 1+ ions in three dimensional clusters of CuO [30]. It is also present in some of the UV-vis spectra of CuO supported by CeO 2 nanorods and polyhedra (but not by ceria cubes) [29]. Unfortunately, Dong et al did not discuss this prominent feature in their spectra.…”

“…5. Compared to CuO/SHS, the ceria-containing samples contain a oxygen-to-Ce 4+ charge-transfer band and an interband transition around 271 and 347 nm, respectively [29]. The samples with Cu/Ce > 1 exhibit a strong and broad absorption band around 700 nm due to the d-d transition of Cu 2+ in octahedral symmetry.…”

Effect of Microgravity on Synthesis of Nano Ceria

“…To the best of our knowledge, there have not been any publications for the synthesis of nanorods under such conditions. In most cases, studies have concluded that ceria nanorods are formed at much higher temperatures and pressures [27,[46][47][48][49]. In order to understand the formation of ceria nanorods under microgravitiy condition, two crystal growth processes, Oswald ripening and oriented attachment, can be considered.…”

The influence of nano-architectured CeO supports in RhPd/CeO2 for the catalytic ethanol steam reforming reaction

“…In fact, shapedependent activity of ceria has already been recognized in catalytic CO oxidation [11][12][13][14], NO reduction [15], water-gas shift reaction [16,17] and soot combustion [18]. The energy required to form oxygen vacancies on the {1 1 1} surface of CeO 2 is higher than those on {1 1 0} and {1 0 0} surfaces, so the concentration of oxygen vacancies on differents planes of ceria is different [19].…”