The reaction mechanisms for CO catalytic oxidation by N2O or O2 on the Co3O4(110) surface were studied by DFT slab calculations. CO chemisorbs preferably at a surface Co3+ site. After the Co3+ site is completely covered, CO adsorbs at the neighboring twofold coordinated surface oxygen atom bonded to Co2+ and Co3+ cations, resulting in the formation of CO2 and an oxygen vacancy with a low energy barrier of 0.033 eV, which rationalizes the experimental observation that Co3O4‐based systems are active for CO oxidation at low temperatures. N2O or O2 interacts with the oxygen vacancy site to regenerate the surface, leaving N2 or the activated O2− species to be attacked by the second CO to yield CO2 to proceed with the catalytic cycle. The CO oxidation reaction follows the Mars– van Krevelen mechanism.
For
oxide-supported metal catalysts, support reducibility and metal
dispersion are the key factors to determine the activity and selectivity
in many essential reactions involving redox process. Herein, we tuned
the exposed surface atoms of the catalyst by facet control and doping
methods, which were simultaneously applied to boost the reducibility
and metal dispersion of an oxide support. Pd supported on Cu-doped
CeO2 (Pd/CDC) for water–gas shift reaction (WGSR)
was considered a model system; Cu was doped into the cubic and octahedral
CeO2 enclosed with (100) and (111) facets, respectively.
By a systematic combination of density functional theory calculations
and experimental analyses, the WGSR activity of the Pd/CDC cube was
verified to synergistically increase by more than just the sum of
the morphology and Cu doping effects. The effect of each tuning method
on the activity was further investigated from a mechanistic perspective.
This work presents a rational design knowledge to enhance the catalytic
activity that can be extended to a wide range of supported metal systems.
Nickel is considered an economically feasible catalyst for the dry reforming of methane (DRM) owing to its high activity. Because the highly endothermic DRM requires a high reaction temperature to...
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