Stabilization of the (110) tetragonal zirconia surface by hydroxyl chemical transformation

Áñez, Rafael; Sierraalta, Aníbal; Martorell, Guillermo; Sautet, Philippe

doi:10.1016/j.susc.2009.05.030

Cited by 22 publications

(17 citation statements)

References 42 publications

(56 reference statements)

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The highly exothermic adsorption of the incipient amounts of water (∆E ads ∼1.5 eV) observed on both (111) and (110) surfaces has also been found in other oxides like TiO 2 , 42 ZrO 2 , 43 and γ-Al 2 O 3 . 44 It can be explained by strong Lewis acidity of the unsaturated cationic centers situated on the surface.…”

Section: Resultsmentioning

confidence: 59%

Periodic Density Functional Theory and Atomistic Thermodynamic Studies of Cobalt Spinel Nanocrystals in Wet Environment: Molecular Interpretation of Water Adsorption Equilibria

et al. 2010

View full text Add to dashboard Cite

In this paper we present a theoretical study of water sorption on cobalt spinel nanocrystals by means of plane-wave periodic density functional theory (DFT) calculations jointly with statistical thermodynamics. The three most stable (100), (110), and (111) planes exposed by Co 3 O 4 were considered, and their stabilization upon water adsorption is discussed in detail. The calculated changes in free enthalpy of the investigated system under different hydration conditions along with the Wulff construction were used to predict the rhombicuboctahedral equilibrium morphology of cobalt spinel nanocrystals in different conditions, which corresponds very well to the experimental transmission electron microscopic (TEM) images. Two-dimensional surface coverage versus temperature and pressure diagrams were constructed for each of the examined (100), (110), and (111) planes to illustrate water adsorption processes in a concise way.

show abstract

Section: Resultsmentioning

confidence: 59%

Periodic Density Functional Theory and Atomistic Thermodynamic Studies of Cobalt Spinel Nanocrystals in Wet Environment: Molecular Interpretation of Water Adsorption Equilibria

et al. 2010

View full text Add to dashboard Cite

show abstract

“…Under working catalytic conditions the surface can become hydroxylated and the process of hydrogen spillover can be affected by the level of hydroxylation of the surface. 81,82 In principle, another reduction mechanism is also possible. At high hydrogen partial pressure, Even considering entropic effects, it is unlikely that the process will take place.…”

Section: Multiple Adsorption Of H 2 Molecules On Ru 10 /Tio 2 and Ru mentioning

confidence: 99%

Hydrogen Adsorption, Dissociation, and Spillover on Ru₁₀ Clusters Supported on Anatase TiO₂ and Tetragonal ZrO₂ (101) Surfaces

2015

View full text Add to dashboard Cite

The scope of this work is to study at atomistic level the mechanism of hydrogen spillover promoted by metal particles on oxide surfaces. By means of Density Functional Theory calculations with Hubbard correction (DFT+U) we have analyzed the adsorption and dissociation of molecular hydrogen on anatase titania, a-TiO 2 (101), and tetragonal zirconia, t-ZrO 2 (101), surfaces in the presence of a supported Ru 10 nanocluster. The role of the supported metal particle is essential as it favours the spontaneous dissociation of H 2 , a process which does not occur on the bare oxide surface. At low hydrogen coverage, the H atoms prefer to stay on the Ru 10 particle, charge accumulates on the metal cluster, and reduction of the oxide does not take place. On a hydroxylated surface, the presence of a Ru nanoparticle is expected to promote the reverse effect, i.e. hydrogen reverse spillover from the oxide to the supported metal. It is only at high hydrogen coverage, resulting in the adsorption of several H 2 molecules on the metal cluster, that it becomes thermodynamically favourable to have hydrogen transfer from the metal to the O sites of the oxide surface. In both TiO 2 and ZrO 2 surfaces the migration of an H atom from the Ru cluster to the surface is accompanied by an electron transfer to the empty states of the support with reduction of the oxide surface.

show abstract

“…1 5,[7][8][9] . Surface protonation 22,23 is an analogous process in which the surface is also reduced by the oxidation of O 2− into O 2 , although in this case the process depends on the presence of water, H 2 O→ 1/2 O 2 +2e − +2H + , and both the energetics and kinetics will be different from the previous one 22 . The protons attach to the surface O atoms, while the electrons are again free to go to the n interface (note that the non-redox hydroxylation, H 2 O→ OH − +H + , does not affect the electrostatics across the film).…”

Section: Introductionmentioning

confidence: 99%

Surface defects and conduction in polar oxide heterostructures

2011

View full text Add to dashboard Cite

The polar interface between LaAlO3 and SrTiO3 has shown promise as a field effect transistor, with reduced (nanoscale) feature sizes and potentially added functionality over conventional semiconductor systems. However, the mobility of the interfacial two-dimensional electron gas (2DEG) is lower than desirable. Therefore to progress, the highly debated origin of the 2DEG must be understood. Here we present a case for surface redox reactions as the origin of the 2DEG, in particular surface O vacancies, using a model supported by first principles calculations that describes the redox formation. In agreement with recent spectroscopic and transport measurements, we predict a stabilization of such redox processes (and hence Ti 3d occupation) with film thickness beyond a critical value, which can be smaller than the critical thickness for 2D electronic conduction, since the surface defects generate trapping potentials that will affect the interface electron mobility. Several other recent experimental results, such as lack of core level broadening and shifts, find natural explanation. Pristine systems will likely require changed growth conditions or modified materials with a higher vacancy free energy.

show abstract

Stabilization of the (110) tetragonal zirconia surface by hydroxyl chemical transformation

Cited by 22 publications

References 42 publications

Periodic Density Functional Theory and Atomistic Thermodynamic Studies of Cobalt Spinel Nanocrystals in Wet Environment: Molecular Interpretation of Water Adsorption Equilibria

Periodic Density Functional Theory and Atomistic Thermodynamic Studies of Cobalt Spinel Nanocrystals in Wet Environment: Molecular Interpretation of Water Adsorption Equilibria

Hydrogen Adsorption, Dissociation, and Spillover on Ru₁₀ Clusters Supported on Anatase TiO₂ and Tetragonal ZrO₂ (101) Surfaces

Surface defects and conduction in polar oxide heterostructures

Contact Info

Product

Resources

About

Stabilization of the (110) tetragonal zirconia surface by hydroxyl chemical transformation

Cited by 22 publications

References 42 publications

Periodic Density Functional Theory and Atomistic Thermodynamic Studies of Cobalt Spinel Nanocrystals in Wet Environment: Molecular Interpretation of Water Adsorption Equilibria

Periodic Density Functional Theory and Atomistic Thermodynamic Studies of Cobalt Spinel Nanocrystals in Wet Environment: Molecular Interpretation of Water Adsorption Equilibria

Hydrogen Adsorption, Dissociation, and Spillover on Ru10 Clusters Supported on Anatase TiO2 and Tetragonal ZrO2 (101) Surfaces

Surface defects and conduction in polar oxide heterostructures

Contact Info

Product

Resources

About

Hydrogen Adsorption, Dissociation, and Spillover on Ru₁₀ Clusters Supported on Anatase TiO₂ and Tetragonal ZrO₂ (101) Surfaces