title: 3D Atomic Arrangement at Functional Interfaces Inside Nanoparticles by Resonant High-Energy X-ray Diffraction.
abstract: With current science and technology moving rapidly into smaller scales, nanometer-sized materials, often referred to as NPs, are produced in increasing numbers and explored for numerous useful applications. Evidence is mounting, however, that useful properties of NPs can be improved further and even new NP functionality achieved by not only controlling the NP size and shape but also interfacing chemically or structurally distinct entities into single, so-called "composite" NPs. A typical example is core-shell NPs wherein the synergy of distinct atoms at the core\shell interface endows the NPs with otherwise unachievable functionality. However, though advantageous, the concept of functional interfaces inside NPs is still pursued largely by trial-and-error. That is because it is difficut to assess the interfaces precisely at the atomic level using traditional experimental techniques and, hence, difficult to take control of. Using the core\shell interface in less than 10 nm in size Ru core-Pt shells NPs as an example, we demonstrate that precise knowledge of the 3D atomic arrangement at functional interfaces inside NPs can be obtained by resonant high-energy X-ray diffraction (XRD) coupled to element-specific atomic pair distribution function (PDF) analysis. On the basis of the unique structure knowledge obtained, we scrutinize the still-debatable influence of core\shell interface on the catalytic functionality of Ru core-Pt shell NPs, thus evidencing the usefulness of this nontraditional technique for practical applications.
authors.affiliation: Department of Physics, Central Michigan University , Mt. Pleasant, Michigan 48859, United States.
authors.forename: Valeri
authors.initials: V
authors.lastname: Petkov
authors.affiliation: Department of Physics, Central Michigan University , Mt. Pleasant, Michigan 48859, United States.
authors.forename: Binay
authors.initials: B
authors.lastname: Prasai
authors.affiliation: X-ray Science Division, Advanced Photon Source, Argonne National Laboratory , Argonne, Illinois 60439, United States.
authors.forename: Sarvjit
authors.initials: S
authors.lastname: Shastri
authors.affiliation: Department of Engineering and System Science, National Tsing Hua University , Hsinchu 30013, Taiwansinchu.
authors.forename: Tsan-Yao
authors.initials: TY
authors.lastname: Chen
keywords: 3D atomic structure; composite metallic nanoparticles for catalytic applications; element specific atomic pair distribution functions; resonant high-energy X-ray diffraction; reverse Monte Carlo simulations