CuO_x/CeO₂ catalysts were prepared by depositing CuO_x clusters onto ceria nanoparticles with different morphologies, including rods, polyhedra, and cubes. These catalysts were evaluated for the reduction of NO with CO. Depending on their morphology these nanoparticles exposed different ceria faces on the surface. Nanorods and nanopolyhedra exposed primarily the (111) faces, while nanocubes showed the (100) faces. The catalytic performance of these catalysts depended strongly on the morphology of the support, that is on the exposed ceria faces and was highest for CuO_x supported on nanorods and nanopolyhedra, while on the nanocubes it was lowest. The focus of our study was the influence of oxygen vacancy defects and their role in the reaction mechanism. The morphology-dependent concentration of oxygen vacancy defects on these catalysts was examined using electron paramagnetic resonance, X-ray photoelectron spectroscopy, and Raman spectroscopy. Among the evaluated CuO_x/CeO₂ catalysts the one based on ceria polyhedra exhibited the best performance, affording full conversion of NO and CO with nearly 100% selectivity to N₂ over 150 h on-stream at 250 °C and a gas hourly space velocity of 36 000 mL g⁻¹ h⁻¹. First-principles calculations indicate that with increasing lattice strain the formation of oxygen vacancies is favored on ceria(111) compared to ceria(100) and shed some light on the crucial role of oxygen vacancy defects in the reaction mechanism.

中文翻译：

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在 CuOx/CeO2 纳米复合材料上用 CO 还原 NO：氧空位和晶格应变的影响

CuO _x /CeO ₂催化剂是通过将CuO _x簇沉积到具有不同形态的氧化铈纳米颗粒上制备的，包括棒状、多面体和立方体。评估了这些催化剂用 CO 还原 NO 的能力。根据它们的形态，这些纳米颗粒在表面暴露不同的氧化铈面。纳米棒和纳米多面体主要暴露（111）面，而纳米立方体显示（100）面。这些催化剂的催化性能很大程度上取决于载体的形态，即在暴露的氧化铈表面上，对于 CuO _x是最高的支撑在纳米棒和纳米多面体上，而在纳米立方体上它是最低的。我们研究的重点是氧空位缺陷的影响及其在反应机制中的作用。使用电子顺磁共振、X 射线光电子能谱和拉曼光谱检查这些催化剂上氧空位缺陷的形态依赖性浓度。在评估的 CuO _x /CeO ₂催化剂中，基于氧化铈多面体的催化剂表现出最好的性能，在 250 °C 和气时空间下运行 150 小时内，NO 和 CO 的完全转化率接近 100% 对 N _{2 的}选择性36 000 mL g ^-1 h ^{-1 的速度}. 第一性原理计算表明，随着晶格应变的增加，与氧化铈（100）相比，氧化铈（111）有利于氧空位的形成，并揭示了氧空位缺陷在反应机制中的关键作用。