Investigation of Local Structure and Enhanced Thermal Stability of Ir-Doped PdRu Nanoparticles for Three-Way Catalytic Applications
Investigation of Local Structure and Enhanced Thermal Stability of Ir-Doped PdRu Nanoparticles for Three-Way Catalytic Applications
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DOI：
10.1021/acs.jpcc.1c05929
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发表时间：
2021-09
期刊：
影响因子：
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通讯作者：
A. Tayal;O. Seo;Jaemyung Kim;K. Kusada;H. Kitagawa;O. Sakata
中科院分区：
文献类型：
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作者：
A. Tayal;O. Seo;Jaemyung Kim;K. Kusada;H. Kitagawa;O. Sakata
利用X射线吸收精细结构谱（XAFS）研究了新合成的PdRuIr和PdRu合金纳米粒子（NPs）的局域结构和热稳定性，并与Ru纳米粒子进行了比较。Pd K-边XAFS表明，一个显着的部分Pd偏析，形成金属NP集群。在PdRuIr NP中，小部分Pd与Ir形成合金，而大部分相是具有新颖面心立方结构的Ru-Ir合金。除了不同的本地环境，XAFS分析显示存在的PdRu和PdRuIr纳米粒子的非谐无序。先前观察到的增强的热稳定性与Pd和Ir掺杂进行了研究，使用温度依赖situXAFS。在Ru纳米颗粒中，在673 K处观察到近边缘特征的突变，而PdRu和PdRuIr纳米颗粒的突变逐渐被抑制。在此温度下，动力学波动更明显的纯钌纳米颗粒，有助于转换成挥发性RuO 4相的表面吸附的O2，从而导致更早的蒸发钌。动态波动抑制合金元素或得到扩展到更高的温度，有助于延迟RuO 4的形成过程，并提高PdRu和PdRuIr纳米颗粒的热稳定性增加的顺序。
The local structure and thermal stability of newly synthesized PdRuIr and PdRu alloy nanoparticles (NPs) were studied using X-ray absorption fine structure spectroscopy (XAFS) and compared with those of Ru NPs. Pd K-edge XAFS reveals that a significant fraction of Pd segregates, forming metal NP clusters. In the PdRuIr NPs, a small fraction of Pd forms an alloy with Ir, whereas a majority phase is Ru–Ir alloy having the novel face-centered cubic structure. Apart from the distinct local surroundings, XAFS analysis revealed the presence of an anharmonic disorder in the PdRu and PdRuIr NPs. The previously observed enhanced thermal stability with Pd and Ir doping was investigated using temperature-dependentin situXAFS. In the Ru NPs, an abrupt change in the near-edge features was observed at 673 K, which was gradually suppressed for PdRu and PdRuIr NPs. At this temperature, the dynamical fluctuations were more pronounced in the pure Ru NPs, helping to convert surface-adsorbed O2into the volatile RuO4phase, thereby leading to earlier evaporation of Ru. Dynamical fluctuation suppresses with alloying elements or gets extended to a higher temperature, helping to delay the RuO4formation process and enhancing the thermal stability of the PdRu and PdRuIr NPs in increasing order.