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Unraveling the Core–Shell Structure of Ligand-Capped Sn/SnOx Nanoparticles by Surface-Enhanced Nuclear Magnetic Resonance, Mössbauer, and X-ray Absorption Spectroscopies
ACS NANO (2014)
  • Loredana Protesescu, ETH Zürich
  • Aaron J. Rossini, Université de Lyon
  • Dominik Kriegner, Johannes Kepler University Linz
  • Maxence Valla, ETH Zürich
  • Antoine de Kergommeaux, Laboratoire d’Electronique Moléculaire
  • Marc Walter, ETH Zürich
  • Kostiantyn V. Kravchyk, ETH Zürich
  • Maarten Nachtegaal, Paul Scherrer Institute
  • Julian Stangl, Johannes Kepler University Linz
  • Bernard Malaman, Université de Lorraine
  • Peter Reiss, Laboratoire d’Electronique Moléculaire
  • Anne Lesage, University of Lyon
  • Lyndon Emsley, University of Lyon
  • Christophe Coperet, ETH Zürich
  • Maksym V. Kovalenko, ETH Zürich
Abstract
A particularly difficult challenge in the chemistry of nanomaterials is the detailed structural and chemical analysis of multicomponent nano-objects. This is especially true for the determination of spatially resolved information. In this study, we demonstrate that dynamic nuclear polarization surface-enhanced solid-state NMR spectroscopy (DNP-SENS), which provides selective and enhanced NMR signal collection from the (near) surface regions of a sample, can be used to resolve the core–shell structure of a nanoparticle. Li-ion anode materials, monodisperse 10–20 nm large tin nanoparticles covered with a ∼3 nm thick layer of native oxides, were used in this case study. DNP-SENS selectively enhanced the weak 119Sn NMR signal of the amorphous surface SnO2 layer. Mössbauer and X-ray absorption spectroscopies identified a subsurface SnO phase and quantified the atomic fractions of both oxides. Finally, temperature-dependent X-ray diffraction measurements were used to probe the metallic β-Sn core and indicated that even after 8 months of storage at 255 K there are no signs of conversion of the metallic β-Sn core into a brittle semiconducting α-phase, a phase transition which normally occurs in bulk tin at 286 K (13 °C). Taken together, these results indicate that Sn/SnOx nanoparticles have core/shell1/shell2 structure of Sn/SnO/SnO2 phases. The study suggests that DNP-SENS experiments can be carried on many types of uniform colloidal nanomaterials containing NMR-active nuclei, in the presence of either hydrophilic (ion-capped surfaces) or hydrophobic (capping ligands with long hydrocarbon chains) surface functionalities.
Keywords
  • dynamic nuclear polarization,
  • solid-state NMR,
  • XA S,
  • tin,
  • nanoparticles,
  • colloidal,
  • core/shell structure,
  • li-ion batteries
Publication Date
February 1, 2014
DOI
10.1021/nn406344n
Publisher Statement
Reprinted (adapted) with permission from ACS NANO, 8(3); 2639-2648. Doi: 10.1021/nn406344n. Copyright 2014 American Chemical Society.
Citation Information
Loredana Protesescu, Aaron J. Rossini, Dominik Kriegner, Maxence Valla, et al.. "Unraveling the Core–Shell Structure of Ligand-Capped Sn/SnOx Nanoparticles by Surface-Enhanced Nuclear Magnetic Resonance, Mössbauer, and X-ray Absorption Spectroscopies" ACS NANO Vol. 8 Iss. 3 (2014) p. 2639 - 2648
Available at: http://works.bepress.com/aaron-rossini/11/