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Beilstein J Nanotechnol. 2012; 3: 75–81.
Published online 2012 January 30. doi:  10.3762/bjnano.3.9
PMCID: PMC3304312

Improvement of the oxidation stability of cobalt nanoparticles

Jörg J Schneider, Associate Editor

Summary

In order to enhance the resistance of cobalt nanoparticles to oxidation in air, the impact of different stabilization strategies on the isothermal oxidation of particle dispersions and powders was kinetically investigated and compared to as-prepared particle preparations. A post-synthesis treatment with different alcohols was employed, and we also investigate the influence of two different polymer shells on the oxidation process. We found a parabolic decrease of the magnetization for all particle charges, indicating that the process is dominated by a diffusion of oxygen to the cobalt core and a radial growth of the oxide layer from the particle surface to the core. A significant deceleration of the oxidation process was observed for all alcohol-passivated particle preparations, and this resulted finally in a stagnation effect. The stabilizing effect increases in the sequence Co@OA/MeOH < Co@OA/EtOH < Co@OA/iPrOH. For polymer-coated particle preparations Co@PCL and Co@PS, the deceleration was even more pronounced. The results demonstrate that cobalt nanoparticles can effectively be protected against oxidation in order to improve their mid- to longterm stability.

Keywords: cobalt nanoparticles, core–shell particles, isothermal oxidation, nanoscale passivation, parabolic rate constant

Abstract

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Articles from Beilstein Journal of Nanotechnology are provided here courtesy of Beilstein-Institut