Dealloying of Cobalt from CuCo Nanoparticles under
Syngas Exposure
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Abstract
The
structure and composition of core–shell CuCo nanoparticles
were found to change as a result of cleaning pretreatments and when
exposed to syngas (CO + H<sub>2</sub>) at atmospheric pressure. In
situ X-ray absorption and photoelectron spectroscopies revealed the
oxidation state of the particles as well as the presence of adsorbates
under syngas. Transmission electron microscopy was used for ex situ
analysis of the shape, elemental composition, and structure after
reaction. The original core–shell structure was found to change
to a hollow CuCo alloy after pretreatment by oxidation in pure O<sub>2</sub> and reduction in pure H<sub>2</sub>. After 30 min of exposure
to syngas, a significant fraction (5%) of the particles was strongly
depleted in cobalt giving copper-rich nanoparticles. This fraction
increased with duration of syngas exposure, a phenomenon that did
not occur under pure CO or pure H<sub>2</sub>. This study suggests
that Co and Cu can each individually contribute to syngas conversion
with CuCo catalysts