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

详细信息    查看全文

• 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 CuOb>xb>-decorated CeOb>2b> nanocubes with a meticulous scrutiny on the role of the CuOb>xb>/CeOb>2b> 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, Nb>2b> adsorption–desorption, and X-ray photoelectron spectroscopy (XPS) techniques. The TEM images show the formation of nanosized CeOb>2b> cubes (∼25 nm) and CuOb>xb> nanoparticles (∼8.5 nm). The TEM–EDS elemental mapping images reveal the uniform decoration of CuOb>xb> nanoparticles on CeOb>2b> nanocubes. The XPS and Raman studies show that the decoration of CuOb>xb> on CeOb>2b> nanocubes leads to improved structural defects, such as higher concentrations of Ce³⁺ ions and abundant oxygen vacancies. It was found that CuOb>xb>-decorated CeOb>2b> nanocubes efficiently catalyze soot oxidation at a much lower temperature (Tb>50b> = 646 K, temperature at which 50% soot conversion is achieved) compared to that of pristine CeOb>2b> nanocubes (Tb>50b> = 725 K) under tight contact conditions. Similarly, a huge 91 K difference in the Tb>50b> values of CuOb>xb>/CeOb>2b> (Tb>50b> = 744 K) and pristine CeOb>2b> (Tb>50b> = 835 K) was found in the loose-contact soot oxidation studies. The superior catalytic performance of CuOb>xb>-decorated CeOb>2b> nanocubes is mainly attributed to the improved redox efficiency of CeOb>2b> at the nanointerface sites of CuOb>xb>–CeOb>2b>, as evidenced by Ce Mb>5,4b> EELS analysis, supported by XRD, Raman, and XPS studies, a clear proof for the role of nanointerfaces in the performance of heterostructured nanocatalysts.