Adsorption and dissociation of methanol on the fully oxidized and partially reduced (111) cerium oxide surface: Dependence on the configuration of the cerium 4f electrons

Methanol Reactivity on Silica-Supported Ceria Nanoparticles

“…Figure 5 suggests that there is no straightforward relationship between the adsorption geometry of methoxy species and their reactivity towards FA. We may only speculate that a relatively higher intensity of the 1108 cm -1 band on particles, commonly assigned to methoxy in atop geometry and which, on the basis of DFT calculations [21], is less stable compared to adsorption on oxygen vacancy, would be consistent with the methanol adsorption on low-coordinated Ce sites present on the particle edges. In addition, the energy of formation of an oxygen vacancy on the surfaces of nanoparticles has been shown to be significantly lower than that of planar surfaces, which leads to much higher oxygen-vacancy concentrations in the nanoparticles, and this property is strongly dependent upon size for small particles [7][8][9].…”

“…DFT study of methanol adsorption on defect-free CeO 2 (111) [20] suggested that dissociative adsorption of methanol by either C−H or O−H bond scission is more favorable than molecular adsorption, but only at low coverages. Another DFT calculation [21] showed that the dissociation of methanol may occur on the regular surface, but it is enhanced by the presence of a vacancy. An on-top methoxy species, where the methoxy oxygen binds to a cerium atom from the second layer, was identified as a dissociation product on the fully oxidized surface.…”

“…On reduced ceria, more methanol can be adsorbed, and it undergoes more extensive decomposition to produce CO and H 2 near 640 K in addition to H 2 O and FA. Ferrizz et al [25], using a CeO 2 (111) single crystal, argued that vacancies on the surface are necessary for methanol adsorption and dissociation, Mullins et al [26] and Siokou and Nix [19] found that those processes also take place on the fully oxidized surface, although the dissociation of methanol on the surface is considerably enhanced in the presence of vacancies [21]. In addition, Ferrizz et al [25] have examined ~ 4 nm-thick ceria films grown on the -Al 2 O 3 (0001) and yttria-stabilized zirconia (100) substrates.…”

An experimental and DFT study of the adsorption and oxidation of NH3 on a CeO2 catalyst modified by Fe, Mn, La and Y

“…Zhou et al [15] synthesized and studied CeO 2 nanorods and revealed that the (1 1 0) and (1 0 0) surfaces were more reactive than the most stable (1 1 1) surface. Beste et al [16] systematically investigated the adsorption/desorption of methanol on oxidized and reduced CeO 2 (1 1 1) surfaces by the PW91 + U method. Recently, Wu et al [17] synthesized CeO 2 materials, exposing various surfaces and detecting oxygen vacancies by in situ Raman spectroscopy.…”

Modifying ceria (111) with a TiO2 nanocluster for enhanced reactivity

“…69-71. Beste et al 70 found two adsorption modes on the perfect (111) surface from DFT+U calculations: molecular and dissociative as methoxy and hydroxyl, with adsorption energies of −0.76 eV and −0.08 eV. Mei et al 71 also used DFT+U to study methanol adsorption at the clean (111) surface.…”