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Nanoparticles of CoOx and Au/CoOx (x is an atomic ratio between 1.00 and
1.33) were prepared to study their catalytic activity towards the CO oxidation. The
oxidation state of cobalt ions in the prepared samples was characterized with TPR
(the temperature programmed reduction) technique. Their catalytic activities towards
the CO oxidation were further tested in a fixed bed flow reactor. The measured
activity generally increased with ratio x in CoOx and Au/CoOx.
Observed variation in
activity was interpreted with a mechanism of competitive CO oxidation by two kinds
of oxygen species, i.e., the oxygen molecularly adsorbed on CoOx surface and the
oxygen ions on the surface of Co3O4 spinel structure.
A deposition of Au
crystallites onto the surface of CoOx not only promoted the catalytic activity but
also altered the kinetic order of CO.
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