Designing CuOx Nanoparticle-Decorated CeO2 Nanocubes for Catalytic Soot Oxidation: Role of the Nanointerface in the Catalytic Performance of Heterostructured Nanomaterials

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• 作者：Putla Sudarsanam ; Brendan Hillary ; Baithy Mallesham ; Bolla Govinda Rao ; Mohamad Hassan Amin ; Ayman Nafady ; Ali M. Alsalme ; B. Mahipal Reddy ; Suresh K. Bhargava
• 刊名：Langmuir
• 出版年：2016
• 出版时间：March 8, 2016
• 年：2016
• 卷：32
• 期：9
• 页码：2208-2215
• 全文大小：456K
• ISSN：1520-5827

文摘

This work investigates the structure–activity properties of CuO_x-decorated CeO₂ nanocubes with a meticulous scrutiny on the role of the CuO_x/CeO₂ nanointerface in the catalytic oxidation of diesel soot, a critical environmental problem all over the world. For this, a systematic characterization of the materials has been undertaken using transmission electron microscopy (TEM), transmission electron microscopy–energy-dispersive X-ray spectroscopy (TEM–EDS), high-angle annular dark-field–scanning transmission electron microscopy (HAADF–STEM), scanning transmission electron microscopy–electron energy loss spectroscopy (STEM–EELS), X-ray diffraction (XRD), Raman, N₂ adsorption–desorption, and X-ray photoelectron spectroscopy (XPS) techniques. The TEM images show the formation of nanosized CeO₂ cubes (∼25 nm) and CuO_x nanoparticles (∼8.5 nm). The TEM–EDS elemental mapping images reveal the uniform decoration of CuO_x nanoparticles on CeO₂ nanocubes. The XPS and Raman studies show that the decoration of CuO_x on CeO₂ nanocubes leads to improved structural defects, such as higher concentrations of Ce³⁺ ions and abundant oxygen vacancies. It was found that CuO_x-decorated CeO₂ nanocubes efficiently catalyze soot oxidation at a much lower temperature (T₅₀ = 646 K, temperature at which 50% soot conversion is achieved) compared to that of pristine CeO₂ nanocubes (T₅₀ = 725 K) under tight contact conditions. Similarly, a huge 91 K difference in the T₅₀ values of CuO_x/CeO₂ (T₅₀ = 744 K) and pristine CeO₂ (T₅₀ = 835 K) was found in the loose-contact soot oxidation studies. The superior catalytic performance of CuO_x-decorated CeO₂ nanocubes is mainly attributed to the improved redox efficiency of CeO₂ at the nanointerface sites of CuO_x–CeO₂, as evidenced by Ce M_5,4 EELS analysis, supported by XRD, Raman, and XPS studies, a clear proof for the role of nanointerfaces in the performance of heterostructured nanocatalysts.