The stability of the hydroxylated (0001) surface of α-Al2O3

Łodziana, Zbigniew; Nørskov, Jens K.; Stoltze, Per

doi:10.1063/1.1574798

Cited by 151 publications

(183 citation statements)

References 27 publications

Supporting

Mentioning

168

Contrasting

Unclassified

Order By: Relevance

“…For example, Wang et al 15 showed that the single Al-terminated surface is stable up to high oxygen partial pressures with large inward relaxations, but that the O-terminated surface can be stabilized by hydrogen. Other calculations have confirmed that hydrogen strongly affects the surface, 3,[16][17][18] and different terminations of the clean and hydrated surface have also been observed experimentally. 19 Moreover, the dissociation mechanism of water on the surface has been thoroughly investigated, and H 2 O has been shown to dissociate readily.…”

Section: Introductionmentioning

confidence: 57%

Ab initiostudies of Al, O, andO2adsorption onα−Al2O3
Wallin
¹
,
Andersson
²
,
Münger
³

et al. 2006
Phys. Rev. B
45
5
39
0
View full text Add to dashboard Cite

The interactions of Al, O, and O 2 with different ␣-Al 2 O 3 ͑0001͒ surfaces have been studied using ab initio density functional theory methods. All three surface terminations obtainable by cleaving the bulk structure ͓single Al-layer ͑AlO͒, double Al-layer ͑AlAl͒, and O terminations͔ have been considered, as well as a completely hydrogenated O-terminated surface. Adsorbed Al shows strong ioniclike interaction with the AlOand O-terminated surfaces, and several metastable adsorption sites are identified on the O-terminated surface. On the completely hydrogenated surface, however, Al adsorption in the bulk position is found to be unstable or very weak for the studied configurations of surface H atoms. Atomic O is found to interact strongly with the AlAl-terminated surface, where also O 2 dissociative adsorption without any appreciable barrier is observed. In contrast, O adsorption on the AlO-terminated surface is metastable relative to molecular O 2 . On the O-terminated surface, we find the creation of O surface vacancies to be plausible, especially upon exposure to atomic O at elevated temperatures. The results are mainly discussed in the context of alumina thin film growth and provide insight into phenomena related to, e.g., preferred adsorption sites and effects of hydrogen on the growth.

show abstract

Section: Introductionmentioning

confidence: 57%

Ab initiostudies of Al, O, andO2adsorption onα−Al2O3
Wallin
¹
,
Andersson
²
,
Münger
³

et al. 2006
Phys. Rev. B
45
5
39
0
View full text Add to dashboard Cite

show abstract

“…29 Moreover, no UV or similar spectroscopic studies have been reported for the clean or hydroxylated surface that may be related to surface F centers. Since the main interests of this work is to identify the role of the vacancy coordination and relaxation in the excitation energies only the simplest clean surface has been considered.…”

Section: Spectroscopic Features Of Surface Vacancy Centersmentioning

confidence: 99%

“…28 Nevertheless, it is worth pointing out that this surface is rather difficult to obtain experimentally due to its rapid hydroxylation. 29,30 The surface O-vacancy models have been obtained by removing a single O atom ͑or O − anion͒ from the relaxed, hydroxyl-free structure. The energies have been determined using the Perdew-Wang ͑PW91͒ implementation 31 of the exchange-correlation functional, this functional belongs to the family of methods developed under the so-called generalized gradient approximation ͑GGA͒.…”

Section: A Periodic Calculationsmentioning

confidence: 99%

First-principles study of the optical transitions ofFcenters in the bulk and on the (0001) surface ofα−Al2O3

et al. 2005

View full text Add to dashboard Cite

The electronic structure and spectroscopic features of the optical spectra of oxygen vacancies in the bulk and on the ͑0001͒ surface of ␣-Al 2 O 3 have been studied by first-principles methods. The effect of oxygen vacancies on the crystalline structure has been determined by the appropriate atomic structure optimization carried out using a periodic model and density functional theory ͑DFT͒ calculations. Both, neutral ͑F center͒ and charged ͑F + center͒ oxygen vacancies have been considered. Optical transitions arising from the excitations of the electron͑s͒ trapped in the F + and F centers, both on the surface and in the bulk of the material, have been studied using a suitable embedded cluster model approach. The cluster geometry, including the relaxation around the vacancy, has been taken from the periodic calculations. The transition energies and intensities have been obtained by applying the explicitly correlated multiconfigurational second-order perturbation theory method and also time-dependent DFT approaches. The present results are in good agreement with available experimental data for the bulk and provide a guide to interpret forthcoming experiments involving the spectroscopy of oxygen vacancies present in irradiated or defective ␣-Al 2 O 3 ͑0001͒ surfaces.

show abstract

“…, and a specific surface area below 10 m 2 g À1 [6]. Both characteristics limit the total amount of surface OH groups [7][8][9].…”

Section: à2mentioning

confidence: 99%

Preparation and particle size effects of Ag/α-Al2O3 catalysts for ethylene epoxidation

Reijen

Kanungo

Welling

et al. 2017

Journal of Catalysis

View full text Add to dashboard Cite

a-AluminaCatalyst design Ethylene oxide Particle size effect a b s t r a c t Currently, for the industrial ethylene epoxidation a-alumina supported silver catalysts are the only catalyst of choice. We demonstrate a novel method to produce these catalysts with different silver particle sizes, but without changing other key parameters that may affect the catalytic performance such as support specific surface area or metal precursor. a-Alumina was impregnated with a silver oxalate solution, and was subsequently dried and treated in different gas atmospheres and at different temperatures to tune the silver particle sizes in the range of 20-500 nm. Particles of 20 nm exhibited a lower turnover frequency than particles of 70 nm and larger, which exhibit a constant turnover frequency, in accordance with results in literature. However, the selectivity, when measured at constant conversion, was particle size independent. This is the first time that the effect of the particle size on the selectivity of ethylene epoxidation is reported at constant conversion. This was made possible by a new method of producing supported silver catalysts, which we expect that is also applicable for silver catalysts with other supports and for the preparation of other supported metal catalysts.

show abstract

The stability of the hydroxylated (0001) surface of α-Al2O3

Cited by 151 publications

References 27 publications

Ab initiostudies of Al, O, andO2adsorption onα−Al2O3
Wallin
¹
,
Andersson
²
,
Münger
³

et al. 2006
Phys. Rev. B
45
5
39
0
View full text Add to dashboard Cite

Ab initiostudies of Al, O, andO2adsorption onα−Al2O3
Wallin
¹
,
Andersson
²
,
Münger
³

et al. 2006
Phys. Rev. B
45
5
39
0
View full text Add to dashboard Cite

First-principles study of the optical transitions ofFcenters in the bulk and on the (0001) surface ofα−Al2O3

Preparation and particle size effects of Ag/α-Al2O3 catalysts for ethylene epoxidation

Contact Info

Product

Resources

About

The stability of the hydroxylated (0001) surface of α-Al2O3

Cited by 151 publications

References 27 publications

Ab initiostudies of Al, O, andO2adsorption onα−Al2O3Wallin1, Andersson2, Münger3 et al. 2006Phys. Rev. B455390View full textAdd to dashboardCite

Ab initiostudies of Al, O, andO2adsorption onα−Al2O3Wallin1, Andersson2, Münger3 et al. 2006Phys. Rev. B455390View full textAdd to dashboardCite

First-principles study of the optical transitions ofFcenters in the bulk and on the (0001) surface ofα−Al2O3

Preparation and particle size effects of Ag/α-Al2O3 catalysts for ethylene epoxidation

Contact Info

Product

Resources

About

Ab initiostudies of Al, O, andO2adsorption onα−Al2O3
Wallin
¹
,
Andersson
²
,
Münger
³

et al. 2006
Phys. Rev. B
45
5
39
0
View full text Add to dashboard Cite

Ab initiostudies of Al, O, andO2adsorption onα−Al2O3
Wallin
¹
,
Andersson
²
,
Münger
³

et al. 2006
Phys. Rev. B
45
5
39
0
View full text Add to dashboard Cite