In Situ Study of Room-Temperature Oxidation Kinetics of Colloidal Co Nanocrystals Investigated by Faraday Rotation Measurement
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Kinetics of oxidation of colloidal Co nanocrystals in organic solvent by the dissolved O2 at room temperature was studied in situ via Faraday rotation measurements. The oxidation of Co nanocrystals occurred on two distinct time scales: very fast (<1 min) initial oxidation followed by slow (hours) oxidation. The degree of oxidation during the fast stage of the oxidation increases with the dissolved O2 concentration. On the other hand, the slow stage of the oxidation exhibits much weaker and more complex dependence on O2 concentration. Once the fast stage of the oxidation is complete, even a large increase in O2 concentration leads to only a very slow additional oxidation regardless of the initial degree of oxidation during the fast stage. The strong dependence of the long-term oxidation kinetics in colloidal Co nanocrystals primarily on O2 concentration at very early times of the oxidation allows a partial control of the degree of oxidation by preoxidizing under controlled oxidizing environment. © 2010 American Chemical Society.
author list (cited authors)
Jia, S., Hsia, C., & Son, D. H.