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Issue 37, 2015
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Radiation-induced formation of Co3O4 nanoparticles from Co2+(aq): probing the kinetics using radical scavengers

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Abstract

The effects of the Co2+ content and different radical scavengers on the kinetics of γ-radiation-induced Co3O4 nanoparticle formation and growth were investigated. There are four distinct stages of particle formation with different oxidation rates. Scavengers and [Co2+]0 affect the oxidation kinetics in the different stages and consequently the final size of the particles formed. Radiolysis model calculations were performed to obtain the time-evolution of the concentrations of key oxidants and reductants, and the effect of scavengers on those concentrations. Based on the model results and experimental data a reaction mechanism for Co3O4 particle formation by γ-irradiation of solutions containing Co2+(aq) is proposed. The main cobalt oxidation reaction changes with time. Oxidation of Co2+(aq) to Co3+(aq) by radiolytically produced ˙OH occurs first in the solution phase. This is followed by spontaneous co-precipitation of mixed CoII/CoIII hydroxide nucleate particles. Adsorption of CoII(ad) followed by surface oxidation of CoII(ad) to CoOOH(ad) by H2O2 grows particles with a solid CoOOH(s) phase. In parallel, the solid-state transformation of CoOOH(s) and CoII(ad) to form Co3O4(s) occurs.

Graphical abstract: Radiation-induced formation of Co3O4 nanoparticles from Co2+(aq): probing the kinetics using radical scavengers

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Publication details

The article was received on 15 May 2015, accepted on 13 Aug 2015 and first published on 17 Aug 2015


Article type: Paper
DOI: 10.1039/C5CP02828K
Author version available: Download Author version (PDF)
Citation: Phys. Chem. Chem. Phys., 2015,17, 24138-24150
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    Radiation-induced formation of Co3O4 nanoparticles from Co2+(aq): probing the kinetics using radical scavengers

    L. M. Alrehaily, J. M. Joseph and J. C. Wren, Phys. Chem. Chem. Phys., 2015, 17, 24138
    DOI: 10.1039/C5CP02828K

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