Methanol Adsorption on the Clean CeO₂(111) Surface:  A Density Functional Theory Study

Abstract

Molecular and dissociative adsorption of methanol at various sites on the stoichiometric CeO 2 (111) surface have been studied using density functional theory periodic calculations. At 0.25 monolayer (ML) coverage, the dissociative adsorption with an adsorption energy of 0.55 eV is slightly favored. The most stable state is the dissociative adsorption of methanol via C-H bond breaking, forming a coadsorbed hydroxymethyl group and hydrogen adatom on two separate O 3C surface sites. The strongest molecular adsorption occurs through an O-Ce 7C connection with an adsorption energy of 0.48 eV. At methanol coverage of 0.5 ML, the dissociative adsorption and the molecular adsorption became competitive. The adsorption energy per methanol molecule for both adsorption modes falls into a narrow range of 0.46-0.55 eV. As methanol coverage increases beyond 0.5 ML, the molecular adsorption becomes more energetically favorable than the dissociative adsorption because of the attractive hydrogen bonding between coadsorbed methanol molecules. At full monolayer, the adsorption energy of molecular adsorption is 0.40 eV per molecule while the adsorption energy for total dissociative adsorption of methanol is only 0.17 eV. The results at different methanol coverages indicate that methanol can adsorb on a defect-free CeO 2 (111) surface, which are also consistent with experimental observations.

Unraveling the structure sensitivity in methanol conversion on CeO2: A DFT+U study

“…Despite all the above and other theoretical works reported in the literature [37][38][39][40][41][42], up to date there is no complete study assessing the selectivity of methanol dehydrogenation on the most representative ceria facets and proving their different behavior as experimentally observed. Herein, we present a thorough mechanistic study on the selective conversion of methanol to formaldehyde and its subsequent conversion to CO. To account for the particular morphology of the three common nanoshapes above, we have studied the three lowest index and energy surfaces (111), (110), and (100) (Fig.…”

The surface chemistry of cerium oxide

“…The chemically important reaction for the adsorption of methanol on The methoxy species can be differentiated spectroscopically from the alcohol based on the C 1s, and especially the O 1s, binding energies [50,208]. In contrast, calculations by Mei et al have indicated that the most stable dissociative state on stoichiometric CeO 2(111) involves cleavage of a C-H bond and the formation of a C-O(l) bond [209]. In a subsequent publication these authors indicated that O-H cleavage may be kinetically favored due to much lower activation barrier compared to C-H cleavage, resulting in adsorbed species that agree with experimental observations [210].…”

Understanding the Role of Surface Oxygen in Hg Removal on Un‐Doped and Mn/Fe‐Doped CeO2(111)

“…CeO 2 (111) surface is stable and the most exposed surface of ceria . The slab was constructed via a p (3 × 3) supercell with nine atomic layers (including 27 Ce atom and 54 O atom) with a 15 å vacuum thickness, as shown in Figure a and b. To simulate Mn‐ and Fe‐doped CeO 2 (111) surfaces, a Mn or Fe atom takes place of one Ce atom, which are Ce 0.96 Mn 0.04 O 2 (111) and Ce 0.96 Fe 0.04 O 2 (111), can be observed in Figure c and d .…”