Division of Materials and Manufacturing Science, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan.
Nanoscale. 2020 Jan 23;12(3):1779-1789. doi: 10.1039/c9nr08899g.
The effect of the morphology, which exposes different crystal planes, on the physicochemical properties and catalytic activity in diesel carbon soot oxidation was studied using CoOx-decorated CeO2 (CoCeO2) heterostructured catalysts, such as nanorods (NRs), nanocubes (NCs), and nanoparticles (NPs). The CoOx/CeO2 nanorods (CoCeO2-NR) showed superior carbon soot combustion activity at lower temperatures to CoCeO2-NCs and CoCeO2-NPs under both tight and loose contact modes with soot combustion temperatures (T50) of 321 and 494 °C, respectively. A comprehensive analysis by means of X-ray diffraction, Raman spectroscopy, high-angle annular dark-field scanning transmission electron microscopy, in situ X-ray absorption fine structure, temperature-programmed reduction, oxygen storage/release measurements, and density functional theory calculations revealed that the improved activity of CoCeO2-NRs is mainly ascribed to the high oxygen release rate and strong redox capability of the supported Co species, with complete reversibility. This originates from the high reactivity of oxygen atoms on (110) surfaces, compared to (100) and (111) surfaces over CeO2. Additionally, CoCeO2-NRs displayed durability and recyclability without any significant loss of catalytic activity or structural change. These insights will aid in the rational design of practical catalysts for the purification of diesel exhaust and other important transformations.
采用 CoOx 修饰的 CeO2（CoCeO2）异质结构催化剂，如纳米棒（NRs）、纳米立方体（NCs）和纳米颗粒（NPs），研究了暴露不同晶面的形态对柴油碳烟氧化的物理化学性质和催化活性的影响。在紧密和松散接触模式下，CoOx/CeO2 纳米棒（CoCeO2-NR）与 CoCeO2-NCs 和 CoCeO2-NPs 相比，在较低温度下具有更好的碳烟燃烧活性，其碳烟燃烧温度（T50）分别为 321°C 和 494°C。通过 X 射线衍射、拉曼光谱、高角度环形暗场扫描透射电子显微镜、原位 X 射线吸收精细结构、程序升温还原、氧储存/释放测量和密度泛函理论计算的综合分析表明，CoCeO2-NRs 活性的提高主要归因于负载 Co 物种的高氧释放率和强氧化还原能力，具有完全的可逆性。这源于 CeO2 上（110）表面的氧原子比（100）和（111）表面的氧原子具有更高的反应性。此外，CoCeO2-NRs 表现出了耐久性和可回收性，没有明显的催化活性损失或结构变化。这些见解将有助于合理设计用于净化柴油尾气和其他重要转化的实用催化剂。
