In situ environmental transmission electron microscopy to determine transformation pathways in supported Ni nanoparticles

Santhosh Chenna, Peter Crozier

Research output: Contribution to journalArticle

32 Citations (Scopus)

Abstract

We have applied in situ environmental transmission electron microscopy (ETEM) to follow the dynamic phase transformations that take place in SiO 2 supported Ni nanoparticles during oxidation and reduction processes. The gas environments used for in situ ETEM studies were relevant to partial oxidation of methane (POM) reaction. In the presence of the CH 4+O 2 gas mixture (in 2:1 ratio) at 400°C, Ni transforms to NiO due to the high O-chemisorption energy. NiO void structures were formed during the oxidation because of the Kirkendall type process where diffusion of Ni cations along NiO grain boundaries is eight orders of magnitude greater than the diffusion of O anions. Reduction was performed under a CO+H 2 mixture at 400°C (in 1:2 ratio) and also in the presence of CH 4 at 500°C. Particle reduction processes also takes place via the diffusion of Ni cations along the NiO grain boundaries leaving NiO on the surface of the nanoparticle. NiO is the phase that is present on the surface of the nanoparticle during the intermediate stage of reduction.

Original languageEnglish (US)
Pages (from-to)1188-1194
Number of pages7
JournalMicron
Volume43
Issue number11
DOIs
StatePublished - Nov 2012

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Transmission Electron Microscopy
Nanoparticles
Cations
Gases
Methane
Carbon Monoxide
Oxidation-Reduction
Anions

Keywords

  • Environmental TEM
  • In situ
  • Nickel
  • Nickel oxide
  • Partial oxidation of methane
  • Phase transformations
  • Syngas

ASJC Scopus subject areas

  • Cell Biology
  • Structural Biology

Cite this

In situ environmental transmission electron microscopy to determine transformation pathways in supported Ni nanoparticles. / Chenna, Santhosh; Crozier, Peter.

In: Micron, Vol. 43, No. 11, 11.2012, p. 1188-1194.

Research output: Contribution to journalArticle

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