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evolution on a clean partially reduced rutile surface and on the same surface precovered with and : The importance of spin conservation
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10.1063/1.2956506
/content/aip/journal/jcp/129/7/10.1063/1.2956506
http://aip.metastore.ingenta.com/content/aip/journal/jcp/129/7/10.1063/1.2956506
View: Figures

Figures

Image of FIG. 1.
FIG. 1.

The top layer of the partially reduced rutile surface. The atoms are labeled as follows: One bridging oxygen atom; two in-plane oxygen; three fivefold-coordinated Ti atoms; and four sixfold-coordinated Ti atoms.

Image of FIG. 2.
FIG. 2.

Some of the lowest energy structures correspond to the molecular and dissociative adsorption on the partially reduced rutile surface. (a) Reaction profiles for oxygen evolution on . Upper diagram (in cyan) is for triplet, lower diagram (in black) is for singlet. (b) adsorbed on a atom away from the vacancy site. (c) adsorbed between two atoms. (d) adsorbed on a atom located next to an oxygen vacancy. (e) adsorbed between two atoms at the vacancy site and a atom adjacent to the oxygen vacancy. (f) adsorbed at the vacancy site. (g) The lowest energy structure corresponding to the dissociative adsorption for : One oxygen atom is healing the vacancy site while the other one is adsorbed over a atom located next to the vacancy site. (h) The lowest energy structure corresponding to the dissociative adsorption for : One oxygen atom is healing the vacancy site, while the other one is adsorbed between two atoms and forming an oxygen molecule with an in-plane oxygen atom of . The relative energies are given with respect to in the gas phase and the bare partially reduced surface. are the activation energies. The dissociation energies are computed using Eq. (2). The energies are in eV and were obtained using the PW91 functional with a supercell and a 12-layer slab. The bridging oxygen vacancy concentration is 16.7%. is the number of unpaired electrons. are the distances (in ) between the two oxygen atoms of . are the total electronic charge on obtained from a Bader analysis (Refs. 60–62); negative numbers indicate electron gain upon adsorption.

Image of FIG. 3.
FIG. 3.

(a) Total and projected DOS of the partially reduced rutile surface aligned with the DOS of an isolated computed in two separate supercells. (b) Total and projected density of states for structure 2(e) in the singlet state . (c) Same as (b) but for the triplet state . (d) Density plot of an eigenstate involving the MO. (e) Density plot of an eigenstate involving the MO. The orbital energies have been shifted relative to the Fermi level of the spin-down electrons. Density plots show equal density surfaces of .

Image of FIG. 4.
FIG. 4.

Some low-energy structures of adsorbed on the partially reduced rutile with preadsorbed on its surface. (a)–(f) are doublet. (g)–(l) are quartet. (a) and (g) adsorbed on a atom away from the vacancy site. (b) adsorbed between two atoms. [(c) and (h)] adsorbed on a atom located next to an oxygen vacancy. (d) The lowest energy structure corresponding to the dissociative adsorption for : One oxygen atom is healing the vacancy site while the other one is adsorbed on a atom located next to an oxygen vacancy. [(e) and (k)] adsorbed at the vacancy site. [(f) and (l)] adsorbed on top of . (j) The lowest energy structure corresponding to the dissociative adsorption for : One oxygen atom is healing the vacancy site while the other one is adsorbed on . The relative energy defined with respect to in the gas phase and adsorbed at its equilibrium position on a partially reduced . are the activation energies. The dissociation energies are computed using Eq. (2). All energies are in eV and were obtained using the PW91 functional with a supercell and a 12-layer slab. The bridging oxygen vacancy concentration is 16.7%. is the number of unpaired electron. are the distances (in ) between the two oxygen atoms of . are the total electronic charge on obtained from a Bader analysis (Refs. 60–62); negative numbers indicate electron gain upon adsorption.

Image of FIG. 5.
FIG. 5.

Relative energies of the two lowest energy structures corresponding to adsorption on the partially reduced rutile surface. (a) The lowest energy structures. (b) The second-lowest energy isomer. The energies are in eV and were obtained with the PW91 functional on a supercell and 12-layer slab. is the number of unpaired electrons.

Image of FIG. 6.
FIG. 6.

evolution on the partially reduced rutile with preadsorbed on its surface for the triplet state. (a) adsorbed on a atom away from the vacancy site. (b) adsorbed between two atoms. (c) adsorbed on a atom located next to an oxygen vacancy. (d) Same as (c) but left the vacancy site and it is adsorbed between two bridging oxygen atoms located in two adjacent rows. (e) Dissociated : One oxygen atom is healing the vacancy site while the other one is adsorbed on a atom located next to an oxygen vacancy in the trough opposite to the one containing . (f) Same as (e) but migrated in the same trough as the oxygen atom adsorbed on top of a atom. (g) The lowest energy structure corresponding to the dissociative adsorption: One oxygen atom is healing the vacancy site while the other one is adsorbed on top of . The relative energies are given with respect to in the gas-phase and adsorbed at its equilibrium position on a partially reduced surface [shown in Fig. 4(a)]. are the activation energies. The dissociation energies are computed using Eq. (2). All energies are in eV and were calculated with the PW91 functional with a supercell and a 12-layer slab.

Image of FIG. 7.
FIG. 7.

evolution on the partially reduced rutile with preadsorbed on its surface for the singlet state. (a) adsorbed on a atom away from the vacancy site. This is the initial singlet state in which the oxygen molecule is not in the same trough as the Au cluster. (b) adsorbed between two atoms. (c) adsorbed on a atom located next to an oxygen vacancy. (d) adsorbed between two atoms at the vacancy site and a atom adjacent to the oxygen vacancy. (e) adsorbed at the vacancy site. (f) Same as (d) but moved away from the vacancy site. (g) Dissociated : One oxygen atom is healing the vacancy site, while the other one is adsorbed on a atom located next to an oxygen vacancy in the trough opposite to the one containing . (h) and (i) are low-lying states corresponding to adsorption at the vacancy site. (j) Same as (e) but diffused away from . (k) Same as (g) but moved away from the oxygen atom adsorbed at the vacancy site. (l) The lowest energy structure corresponding to the dissociative adsorption: One oxygen atom is healing the vacancy site, while the other one is adsorbed on top of . (m) Dissociated : One oxygen atom is healing the vacancy site while the other one is adsorbed on a atom located next to an oxygen vacancy in the same trough containing . The relative energies are given with respect to in the gas phase and adsorbed at its equilibrium position on a partially reduced surface [shown in Fig. 4(a)]. are the activation energies. All energies are in eV and were calculated with the PW91 functional with a supercell and a 12-layer slab.

Image of FIG. 8.
FIG. 8.

Same as Fig. 7 but is initially adsorbed on a atom located in the same trough as . (a) adsorbed on a atom away from the vacancy site. (b) adsorbed between two atoms. (c) dissociation away from the vacancy site: The oxygen atoms are adsorbed on two different atoms. (d) One oxygen atom moves on top of . (e) The oxygen atom on top of heals the vacancy site. (f) The lowest energy structure corresponding to the dissociative adsorption: One oxygen atom is healing the vacancy site while the other one is adsorbed on top of . (g) adsorbed on a atom located next to an oxygen vacancy. are the distances (in ) between the two oxygen atoms of . are the total electronic charge on obtained from a Bader analysis (Refs. 60–62); negative numbers indicate electron gain upon adsorption.

Image of FIG. 9.
FIG. 9.

Lowest energy structures corresponding to the molecular and dissociative adsorption on gas-phase clusters ( and ). The relative energies are given with respect to gas-phase and the bare clusters in their lowest energy structure. A negative number indicates that adsorption is exothermic. The dissociation energies are computed using Eq. (2). A negative number indicates that dissociation is exothermic. are the activation energies for dissociation. The energies are in eV and were obtained with the PW91 functional in a cubic supercell. is the number of unpaired electrons.

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2008-08-19
2014-04-17
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752b84549af89a08dbdd7fdb8b9568b5 journal.articlezxybnytfddd
Scitation: O2 evolution on a clean partially reduced rutile TiO2(110) surface and on the same surface precovered with Au1 and Au2: The importance of spin conservation
http://aip.metastore.ingenta.com/content/aip/journal/jcp/129/7/10.1063/1.2956506
10.1063/1.2956506
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