Methanol interaction over Cu-Pt clusters supported on CeO2: Towards an understanding of adsorption sites
Por:
Buendia, Fernando G., Araiza, Daniel, Lopez-Rodriguez, Luis, Paz-Borbon, Lauro Oliver, Diaz, Gabriela
Publicada:
1 jun 2022
Resumen:
For the first time, the present work shows a combined theoretical and
experimental analysis of the preferred adsorption sites for both
methanol and methoxy species over Cu, Pt, and bimetallic Cu-Pt clusters
- up to 5 atoms in size - supported on CeO2(111) as model systems. DFT+U
calculations compared to methanol adsorption experiments followed by
DRIFT spectroscopy over Cu, Pt, and bimetallic Cu-Pt nanoparticles
supported over CeO2 octahedra, exposing only {111 crystal planes.
From our DFT+U calculations, we found that methanol adsorption over the
CuPt/CeO2(111) system is slightly favored, compared to the pristine
CeO2(111) surface. Similarly, methoxy species formed through methanol
dehydrogenation (CH3O- + H+) adsorb preferably over the metallic
clusters, compared to the pristine oxide surface. This promotion is
explained by the higher coordination of the methoxy species over the
cluster, especially for those containing a higher amount of Cu atoms.
This results highlights the oxidized Cu sites' role in the catalytic
process, followed by the surface cerium atoms reduction of the support.
The interaction of methanol with the substrate oxygen weakens the O-H
bond, which results in a reduction in the energy barrier when the
reaction occurs on the surface and interface, compared when this occurs
exclusively on the metal cluster. However, after this step, the
potential energy surface's depth suggests that methoxy species prefer to
be adsorbed over the metal clusters. Experimentally, methanol was
adsorbed over Cu, Pt, and bimetallic Cu-Pt nanoparticles supported over
CeO2 {111-octahedral particles. Through in-situ DRIFTS, bands related
to adsorbed methanol and methoxy species were identified. A blue shift
in all the bands was observed, related to metals' influence in adsorbed
species' vibrational mode. In the experimental spectra, new
contributions in Cu-containing catalysts appeared, which were identified
as adsorbed species over the metallic cluster and the interface,
rationalized by calculated spectra.
Filiaciones:
Buendia, Fernando G.:
Instituto de Física, Departamento de Física Química, Universidad Nacional Autónoma de México, Ciudad de México, C.P. 04510, Mexico
Univ Nacl Autonoma Mexico, Inst Fis, Dept Quim Fis, Mexico City 04510, DF, Mexico
Araiza, Daniel:
Instituto de Física, Departamento de Física Química, Universidad Nacional Autónoma de México, Ciudad de México, C.P. 04510, Mexico
Univ Nacl Autonoma Mexico, Inst Fis, Dept Quim Fis, Mexico City 04510, DF, Mexico
Lopez-Rodriguez, Luis:
Instituto de Física, Departamento de Física Química, Universidad Nacional Autónoma de México, Ciudad de México, C.P. 04510, Mexico
Univ Nacl Autonoma Mexico, Inst Fis, Dept Quim Fis, Mexico City 04510, DF, Mexico
Paz-Borbon, Lauro Oliver:
Instituto de Física, Departamento de Física Química, Universidad Nacional Autónoma de México, Ciudad de México, C.P. 04510, Mexico
Univ Nacl Autonoma Mexico, Inst Fis, Dept Quim Fis, Mexico City 04510, DF, Mexico
Diaz, Gabriela:
Instituto de Física, Departamento de Física Química, Universidad Nacional Autónoma de México, Ciudad de México, C.P. 04510, Mexico
Univ Nacl Autonoma Mexico, Inst Fis, Dept Quim Fis, Mexico City 04510, DF, Mexico
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