Oxidation behavior of cobalt nanoparticles studied by in situ environmental transmission electron microscopy

Research output: Contribution to journalArticle

Authors

  • Dejiong Zhang
  • Chuanhong Jin
  • Zi Li
  • Ze Zhang
  • Jixue Li

Colleges, School and Institutes

External organisations

  • State Key Laboratory of Silicon Materials, School of Materials Science and Engineering, Zhejiang University

Abstract

The dynamics of oxidation of cobalt nanoparticles were directly revealed by in situ environmental transmission electron microscopy. Firstly, cobalt nanoparticles were oxidized to polycrystalline cobalt monoxide, then to polycrystalline tricobalt tetroxide, in the presence of oxygen with a low partial pressure. Numerous cavities (or voids) were formed during the oxidation, owing to the Kirkendall effect. Analysis of the oxides growth suggested that the oxidation of cobalt nanoparticles followed a parabolic rate law, which was consistent with diffusion-limited kinetics. In situ transmission electron microscopy allowed potential atomic oxidation pathways to be considered. The outward diffusion of cobalt atoms inside the oxide layer controlled the oxidation, and formed the hollow structure. Irradiation by the electron beam, which destroyed the sealing effect of graphite layer coated on the cobalt surface and resulted in fast oxidation rate, played an important role in activating and promoting the oxidations. These findings further our understanding on the microscopic kinetics of metal nanocrystal oxidation and knowledge of energetic electrons promoting oxidation reaction.

Details

Original languageEnglish
Pages (from-to)775-778
JournalScience Bulletin
Volume62
Issue number11
Early online date10 May 2017
Publication statusPublished - 15 Jun 2017

Keywords

  • Cobalt , Nanoparticle , Oxidation dynamics , Parabolic rate , Environmental transmission electron microscopy (ETEM) , Electron irradiation