Investigation of microstructure and hydrogen absorption properties of bulk immiscible AgRh alloy nanoparticles
Investigation of microstructure and hydrogen absorption properties of bulk immiscible AgRh alloy nanoparticles
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DOI：
10.1016/j.jallcom.2021.159268
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发表时间：
2021-02
影响因子：
6.2
通讯作者：
A. Tayal;O. Seo;Jaemyung Kim;K. Kusada;Hirokazu Kobayashi;H. Kitagawa;O. Sakata
中科院分区：
文献类型：
--
作者：
A. Tayal;O. Seo;Jaemyung Kim;K. Kusada;Hirokazu Kobayashi;H. Kitagawa;O. Sakata
相对于单金属纳米颗粒，双金属合金纳米颗粒（纳米颗粒）表现出上级的催化和化学储存性能。以前，据报道，AgRh形成固溶体合金纳米颗粒，其具有在单个Ag和Rh纳米颗粒中不常见的不寻常的储氢性能。在这里，我们使用的X射线衍射（XRD）和X射线吸收精细结构光谱（XAFS）技术相结合，以调查的微观结构和独特的吸氢性能散装不混溶的AgRh合金纳米颗粒。XRD分析表明，合金样品的长程结构可以被估计为一个单一的fcc相，其晶格参数比体相Ag的晶格参数略小，而比体相Rh的晶格参数大。XAFS分析表明，Rh和Ag之间的电荷转移发生在这个界面区域。近边缘的配置文件揭示了各种本地环境的Ag和Rh，包括不同的原子对距离和无序。原子对距离在Ag周围被压缩，在Rh周围被拉长。样品的大部分是通过混合Rh和Ag NP的纳米/亚纳米尺寸域形成的合金相。原子级的混合主要发生在界面区域。因此，界面区域对微观结构具有重要影响，并为氢吸收提供活性位点。
Bimetallic alloy nanoparticles (NPs) exhibit superior catalytic and chemical storage properties relative to the monometallic NPs. Previously, it has been reported that bimetallic AgRh forms solid-solution alloy NPs that have unusual hydrogen storage properties not commonly observed in individual Ag and Rh NPs. Here, we use a combination of X-ray diffraction (XRD) and X-ray absorption fine structure spectroscopy (XAFS) techniques to investigate the microstructure and unique hydrogen absorption properties of bulk immiscible AgRh alloy NPs. XRD analysis reveals that the long-range structure of the alloy sample can be estimated as a single fcc phase with a slightly smaller lattice parameter than that of the bulk Ag and larger than that of bulk Rh. XAFS analysis reveals that charge transfer between Rh and Ag occurs in this interfacial region. The near-edge profile reveals a variety of local environments for Ag and Rh, including distinct atomic pair distances and disorder. The atomic pair distances were compressed around Ag and elongated around Rh. A substantial fraction of the sample is an alloy phase formed by mixing of nano/sub-nanosized domains of Rh and Ag NPs. Mixing at the atomic level mainly occurs in the interfacial region. Consequently, the interfacial region has an important influence over the microstructure and provides active sites for hydrogen absorption.