Electronic Structure and Redox Properties of the Ti-Doped Zirconia (111) Surface

Chauke, Hasani; Murovhi, Phathutshedzo; Ngoepe, Phuti E.; Leeuw, Nora H. de; Grau‐Crespo, Ricardo

doi:10.1021/jp103181q

Cited by 21 publications

(17 citation statements)

References 78 publications

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“…Fig. 6 assembles the structures of the m-ZrO 2 /(H 2 O) [2][3] complexes that provide the greatest stabilization of the respective surfaces. The gradual decay in the differential adsorption energies upon increase of the water content might suggest that addition of the forth molecule to the computational cells would provide even weaker stabilization, since the molecule would only physisorb and form a multilayer structure via hydrogen bonding.…”

Section: Stabilization Of M-zro 2 Surfaces At Different Water Contentmentioning

confidence: 99%

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Understanding Structure and Stability of Monoclinic Zirconia Surfaces from First-Principles Calculations

Bazhenov

Honkala

2016

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Under the water-rich pre-treatment and/or reaction conditions, structure and chemistry of the monoclinic zirconia surfaces are strongly influenced by oxygen vacancies and incorporated water. Here, we report a combined first-principles and atomistic thermodynamics study on the structure and stability of selected surfaces of the monoclinic zirconia. Our results indicate that among the studied surfaces, the most stable (111) surface is the least vulnerable towards oxygen vacancies in contrast to the less stable (011) and (101) surfaces, where formation of oxygen vacancies is energetically more favorable. Furthermore, we present a vigorous, systematic screening of water incorporation onto the studied surfaces. We observe that the greatest stabilization of the surfaces is achieved when a part of the adsorbed water molecules is dissociated. Nevertheless, the importance of water dissociation for achieving the greatest stabilization is high for the less stable (011) and (101) surfaces, while completely hydrated (111) surface is stabilized equally regardless of the water dissociation state. Analysis of the constructed phase diagrams reveals that the (111) surface remains preferably clean and the (011) and (101) surfaces have dissociated water at low coverage under the reactive conditions of T = 600-900 K and p(H 2 O) < 1 bar. Upon temperature decrease and/or pressure increase, all studied surfaces gradually uptake water until fully hydrated. All in all, our findings complement and broaden the existing picture of the structure and stability of the monoclinic zirconia surfaces under the pre-treatment and/or reaction conditions, enabling rationalization of the potential roles of zirconia as a heterogeneous support and a catalyst component.

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Section: Stabilization Of M-zro 2 Surfaces At Different Water Contentmentioning

confidence: 99%

“…[39,43,29,5,2,3]), focusing significantly less on the most stable m-ZrO 2 form. Foster et al reported an evaluation of charged and neutral vacancies in the m-ZrO 2 bulk.…”

Section: Introductionmentioning

confidence: 99%

Understanding Structure and Stability of Monoclinic Zirconia Surfaces from First-Principles Calculations

Bazhenov

Honkala

2016

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“…This correction, which is proportional to a parameter U eff , has the effect of penalising the hybridisation of the specified orbitals of the metal atoms (Ti 3d orbitals) with the ligands (O atoms), thus counteracting the artificial delocalisation that results from the spurious electron self-interaction in local-exchange DFT [38]. A value of U eff = 3 eV was used in this work, as in some previous studies [39][40][41]. This value was found by Nolan et al to be optimal to reproduce the experimental electronic structure of Ti rich nonstoichiometric TiO 2 surfaces with partial 3d occupancy [39].…”

Section: Density Functional Theory Calculationsmentioning

confidence: 99%

Adsorption of organic molecules at the TiO2(110) surface: The effect of van der Waals interactions

et al. 2015

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Abstract. Understanding the interaction of organic molecules with TiO 2 surfaces is important for a wide range of technological applications. While density functional theory (DFT) calculations can provide valuable insight about these interactions, traditional DFT approaches with local exchangecorrelation functionals suffer from a poor description of non-bonding van der Waals (vdW) interactions. We examine here the contribution of vdW forces to the interaction of small organic molecules (methane, methanol, formic acid and glycine) with the TiO 2 (110) surface, based on DFT calculations with the optB88-vdW functional, which incorporate non-local correlation. The adsorption geometries and energies at different configurations were also obtained in the standard generalized gradient approximation (GGA-PBE) for comparison. We find that the optB88-vdW consistently gives shorter surface adsorbate-to-surface distances and slightly stronger interactions than PBE for the weak (physisorbed) modes of adsorption. In the case of strongly adsorbed (chemisorbed) molecules both functionals give similar results for the adsorption geometries, and also similar values of the relative energies between different chemisorption modes for each molecule. In particular both functionals predict that dissociative adsorption is more favourable than molecular adsorption for methanol, formic acid and glycine, in general agreement with experiment. The dissociation energies obtained from both functionals are also very similar, indicating that vdW interactions do not affect the thermodynamics of surface deprotonation. However, the optB88-vdW always predicts stronger adsorption than PBE. The comparison of the methanol adsorption energies with values obtained from a Redhead analysis of temperature programmed desorption data suggests that optB88-vdW significantly overestimates the adsorption strength, although we warn about the uncertainties involved in such comparisons.

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“…However, these Bader charges are consistent with literature results for Ce 4+ [ 42 ] and Ti 4+ . [ 43 ] Upon introduction of an oxygen vacancy at the interface on the CeO 2 side, the two Ce ions next to the vacancy are partially reduced as the net Bader charge on these ions decreases to 2.0e, consistent with the formation of formally Ce 3+ ions. In contrast, the Ti ions across the interface are not reduced.…”

Section: Density Functional Theory Calculationsmentioning

confidence: 92%

Linking Interfacial Step Structure and Chemistry with Locally Enhanced Radiation‐Induced Amorphization at Oxide Heterointerfaces

Aguiar

Dholabhai

et al. 2014

Adv Materials Inter

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Nanostructured materials and their interfaces have attracted recent interest for their functionality in a wide variety of different applications. However, the origins of these properties in several instances remain unknown. One promising aspect of nanomaterials is their role in materials design for mitigating radiation damage. In particular, engineered radiation tolerant materials would exploit the presence of internal interfaces to act as recombination centers and suppress damage accumulation. Realizing this promise, however, requires a fundamental understanding of how radiation‐induced defects interact with interfaces. Thus, studying the interfacial atomic structure and chemistry before and after irradiation is critical. In this study, we have performed transmission electron microscopy on a series of pristine and ion‐irradiated oxide interfaces to probe radiation‐induced effects. The CeO2/SrTiO3 interface, chosen as a model system for these studies, is characterized by differences in SrTiO3 terminations or steps. Our salient result is that steps are centers for preferential amorphization in SrTiO3, which we attribute to defect flow across the interface induced by non‐stoichiometry in CeO2. The study concludes the interfacial atomic ordering in the form of steps thereby modifies the response to ion irradiation and suggests interface patterning as another parameter to functionalize radiation tolerant materials.

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Electronic Structure and Redox Properties of the Ti-Doped Zirconia (111) Surface

Cited by 21 publications

References 78 publications

Understanding Structure and Stability of Monoclinic Zirconia Surfaces from First-Principles Calculations

Understanding Structure and Stability of Monoclinic Zirconia Surfaces from First-Principles Calculations

Adsorption of organic molecules at the TiO2(110) surface: The effect of van der Waals interactions

Linking Interfacial Step Structure and Chemistry with Locally Enhanced Radiation‐Induced Amorphization at Oxide Heterointerfaces

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