Water (Non-)Interaction with MoO<sub>3</sub>

Head, Ashley R.; Gattinoni, Chiara; Trotochaud, Lena; Yu, Yi; Karslıoğlu, Osman; Pletincx, Sven; Eichhorn, Bryan W.; Bluhm, Hendrik

doi:10.1021/acs.jpcc.9b03822

Cited by 39 publications

(22 citation statements)

References 48 publications

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“…The results at low RH and high RH resemble that seen in other oxides and follow a similar pattern [14][15][16]18,42 with notable exceptions. 20 At low RH (below ∼10 −3 ), water dissociates to form OH groups, which on STO should create Ti−OH and a neighboring O b H on the defect-free surface. While hydroxylation of the surface saturates at high RH (above ∼10 −1 RH), water layers grow above it.…”

Section: ■ Experimental Resultsmentioning

confidence: 99%

“…13 Ambient pressure X-ray photoelectron spectroscopy (AP-XPS) provides a unique opportunity to investigate the surface under increasing ambient relative humidity (RH), where the first hydration layer accrues on the surface from vacuum conditions. This technique has been utilized to studying hydroxide (OH) and water (H 2 O) coverages on transitionmetal oxides, such as TiO 2 , 14,15 MgO, α-Fe 2 O 3 , 6,18 Cu 2 O, 19 Al 2 O 3 , CoOOH 5 , MoO 3 , 20 Sr 2 Co 2 O 5 , 21 and LaCoO 3 , 22 among many other material surfaces.…”

Section: ■ Introductionmentioning

confidence: 99%

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Accuracy in Resolving the First Hydration Layer on a Transition-Metal Oxide Surface: Experiment (AP-XPS) and Theory

et al. 2020

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Understanding the equilibrium conditions at the metal oxide/ aqueous interface is a key component toward visualizing the structure of water in confined environments and differentiating the catalytic activity of transition-metal oxides. While ambient pressure X-ray photoelectron spectroscopy (AP-XPS) has been the primary technique to investigate the formation of a hydration layer on many surfaces, results over the extended relative humidity (RH) range accessible experimentally have not been compared quantitatively to theoretical predictions. With the use of first-principles theoretical methods and accumulated knowledge of AP-XPS spectral analysis, we do so here for a model surface, TiO 2 -terminated undoped SrTiO 3 (100) (STO). The measured distribution of OH and H 2 O coverages from vacuum up to the first hydration layer is in good agreement with a static density functional theory (DFT) configuration involving partial dissociation of H 2 O per Ti-atom mediated by H-bonding. Furthermore, ab initio molecular dynamics (AIMD) simulations at 300 K for select coverages (1/4, 1/2, and 1 ML) test the role of fluctuations and entropy in the competition between adsorption and dissociation with coverage. This comparison between theory and experiment for OH and H 2 O coverages on STO provides a foundation for a more quantitative assessment of the first hydration layer and associated competition between adsorption, dissociation, and H-bonding on transition-metal oxide surfaces.

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Section: ■ Experimental Resultsmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

Accuracy in Resolving the First Hydration Layer on a Transition-Metal Oxide Surface: Experiment (AP-XPS) and Theory

et al. 2020

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“…[56] Water dissociation and chemical reactions are enhanced on defective surfaces in comparison to defect-free ones. [57,58] Interestingly, the electrochemical measurements indicate a higher activity of the (100) surface towards the hydrogen adsorption reaction. Indeed, in Fig.…”

Section: Adsorption In An Electrolytementioning

confidence: 99%

Origin of Surface Reduction upon Water Adsorption on Oriented NiO Thin Films and Its Relation to Electrochemical Activity

et al. 2022

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“…The same model surface containing an O vac and hydroxyl groups approximates the experimental surface characterized with XPS . Our prior work found that small amounts (we estimate ∼5% of a monolayer, just above the detection limit of XPS) of molecular water adsorb to the MoO 3 under the humid conditions used in gas filtration, so the interaction between NO 2 and a MoO 3 (010) surface with adsorbed water molecules was also investigated. The most stable geometric configurations are depicted in Figure , and the corresponding energies are listed in Table .…”

Section: Resultsmentioning

confidence: 99%

NO₂ Interactions with MoO₃ and CuO at Atmospherically Relevant Pressures

Karagoz

Tsyshevsky²,

Trotochaud

et al. 2021

J. Phys. Chem. C

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NO x concentrations in some geographic regions are harmful to human health. Gas filters to trap NO x and other toxic chemicals contain metal oxides, including MoO 3 and CuO. These materials are also being investigated for NO x gas sensors. In a step to understand the fundamental adsorption mechanism in sensors and the effect on binding site availability in gas filters, ambient-pressure X-ray photoelectron spectroscopy (APXPS) was used to study the interaction of NO 2 with polycrystalline MoO 3 and CuO surfaces under pressures up to 0.01 Torr (14 parts per million volume (ppmv)). Density functional theory-based computational modeling was performed to reveal the mechanisms of NO 2 interactions with the MoO 3 (010) and CuO(111) surfaces to aid interpretation of the experimental results. With pressure dependence, NO 2 interacts with reduced Mo 5+ atoms generated by oxygen vacancies and abstracts hydrogen atoms from hydroxyl groups on MoO 3 without accumulating N-containing species on the surface; vacancy-induced electronic states in the band gap are also removed, hinting toward an increase in the resistivity of the material. N-containing species begin accumulating on the CuO surface at atmospherically relevant pressures of 140 ppbv. NO 2 only decomposes at oxygen vacancy sites of CuO. The nitrogen species leave the CuO surface upon evacuation, highlighting the importance of in situ surface characterization when studying gas sensing and adsorption mechanisms. These results imply that NO 2 removes hydroxyl and O vac binding sties on these materials when used in gas filtration and sensing applications. Furthermore, the results show the key role of O vac sites in the gas sensing mechanism of MoO 3 and highlight the potential of APXPS for further studies of gas sensors.

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Water (Non-)Interaction with MoO₃

Cited by 39 publications

References 48 publications

Accuracy in Resolving the First Hydration Layer on a Transition-Metal Oxide Surface: Experiment (AP-XPS) and Theory

Accuracy in Resolving the First Hydration Layer on a Transition-Metal Oxide Surface: Experiment (AP-XPS) and Theory

Origin of Surface Reduction upon Water Adsorption on Oriented NiO Thin Films and Its Relation to Electrochemical Activity

NO₂ Interactions with MoO₃ and CuO at Atmospherically Relevant Pressures

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Water (Non-)Interaction with MoO3

Cited by 39 publications

References 48 publications

Accuracy in Resolving the First Hydration Layer on a Transition-Metal Oxide Surface: Experiment (AP-XPS) and Theory

Accuracy in Resolving the First Hydration Layer on a Transition-Metal Oxide Surface: Experiment (AP-XPS) and Theory

Origin of Surface Reduction upon Water Adsorption on Oriented NiO Thin Films and Its Relation to Electrochemical Activity

NO2 Interactions with MoO3 and CuO at Atmospherically Relevant Pressures

Contact Info

Product

Resources

About

Water (Non-)Interaction with MoO₃

NO₂ Interactions with MoO₃ and CuO at Atmospherically Relevant Pressures