Stability of Core-Shell Nanoparticles for Catalysis at Elevated Temperatures: Structural Inversion in the Ni-Au System Observed at Atomic Resolution

Publikation: Beitrag in einer FachzeitschriftArtikelForschungBegutachtung

Abstract

We present in situ transmission electron microscopy (TEM) studies of nanoscale Ni-Au core-shell particles on heatable TEM grids. The bimetallic clusters, grown fully inert within superfluid helium nanodroplets to avoid any template or solvent effects, are deposited on amorphous carbon and monitored through a heating cycle from room temperature to 400 °C and subsequent cooling. Diffusion processes, known to impair the catalytic activities of core-shell structures, are studied as a function of the temperature and quantified through fits of a temperature-dependent diffusion constant directly derived from the experiment. After cooling, spatially resolved energy-dispersive X-ray spectroscopy and electron energy loss spectroscopy measurements prove the inversion of the core-shell structure from Ni-Au to Au-Ni. Furthermore, a strong oxidation of the now exposed Ni shell is observed in the latter case. In combination with theoretical studies employing density functional theory, we analyze the influence of oxygen on the observed intermetallic diffusion.

Originalspracheenglisch
Seiten (von - bis)1113-1120
Seitenumfang8
FachzeitschriftChemistry of Materials
Jahrgang30
Ausgabenummer3
DOIs
PublikationsstatusVeröffentlicht - 13 Feb 2018

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Catalysis
Nanoparticles
Shells (structures)
Transmission electron microscopy
Cooling
Superfluid helium
Electron energy loss spectroscopy
Amorphous carbon
Temperature
Intermetallics
Density functional theory
Catalyst activity
Oxygen
Heating
Oxidation
Experiments
X-Ray Emission Spectrometry

ASJC Scopus subject areas

  • !!Chemistry(all)
  • !!Chemical Engineering(all)
  • !!Materials Chemistry

Fields of Expertise

  • Advanced Materials Science

Dies zitieren

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abstract = "We present in situ transmission electron microscopy (TEM) studies of nanoscale Ni-Au core-shell particles on heatable TEM grids. The bimetallic clusters, grown fully inert within superfluid helium nanodroplets to avoid any template or solvent effects, are deposited on amorphous carbon and monitored through a heating cycle from room temperature to 400 °C and subsequent cooling. Diffusion processes, known to impair the catalytic activities of core-shell structures, are studied as a function of the temperature and quantified through fits of a temperature-dependent diffusion constant directly derived from the experiment. After cooling, spatially resolved energy-dispersive X-ray spectroscopy and electron energy loss spectroscopy measurements prove the inversion of the core-shell structure from Ni-Au to Au-Ni. Furthermore, a strong oxidation of the now exposed Ni shell is observed in the latter case. In combination with theoretical studies employing density functional theory, we analyze the influence of oxygen on the observed intermetallic diffusion.",
author = "Martin Schnedlitz and Maximilian Lasserus and Ralf Meyer and Daniel Knez and Ferdinand Hofer and Ernst, {Wolfgang E.} and Hauser, {Andreas W.}",
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T1 - Stability of Core-Shell Nanoparticles for Catalysis at Elevated Temperatures

T2 - Structural Inversion in the Ni-Au System Observed at Atomic Resolution

AU - Schnedlitz, Martin

AU - Lasserus, Maximilian

AU - Meyer, Ralf

AU - Knez, Daniel

AU - Hofer, Ferdinand

AU - Ernst, Wolfgang E.

AU - Hauser, Andreas W.

PY - 2018/2/13

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N2 - We present in situ transmission electron microscopy (TEM) studies of nanoscale Ni-Au core-shell particles on heatable TEM grids. The bimetallic clusters, grown fully inert within superfluid helium nanodroplets to avoid any template or solvent effects, are deposited on amorphous carbon and monitored through a heating cycle from room temperature to 400 °C and subsequent cooling. Diffusion processes, known to impair the catalytic activities of core-shell structures, are studied as a function of the temperature and quantified through fits of a temperature-dependent diffusion constant directly derived from the experiment. After cooling, spatially resolved energy-dispersive X-ray spectroscopy and electron energy loss spectroscopy measurements prove the inversion of the core-shell structure from Ni-Au to Au-Ni. Furthermore, a strong oxidation of the now exposed Ni shell is observed in the latter case. In combination with theoretical studies employing density functional theory, we analyze the influence of oxygen on the observed intermetallic diffusion.

AB - We present in situ transmission electron microscopy (TEM) studies of nanoscale Ni-Au core-shell particles on heatable TEM grids. The bimetallic clusters, grown fully inert within superfluid helium nanodroplets to avoid any template or solvent effects, are deposited on amorphous carbon and monitored through a heating cycle from room temperature to 400 °C and subsequent cooling. Diffusion processes, known to impair the catalytic activities of core-shell structures, are studied as a function of the temperature and quantified through fits of a temperature-dependent diffusion constant directly derived from the experiment. After cooling, spatially resolved energy-dispersive X-ray spectroscopy and electron energy loss spectroscopy measurements prove the inversion of the core-shell structure from Ni-Au to Au-Ni. Furthermore, a strong oxidation of the now exposed Ni shell is observed in the latter case. In combination with theoretical studies employing density functional theory, we analyze the influence of oxygen on the observed intermetallic diffusion.

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