Coupling Ambient Pressure X-ray Photoelectron Spectroscopy with Density Functional Theory to Study Complex Surface Chemistry and Catalysis

Head, Ashley R.; Trotochaud, Lena; Tsyshevsky, Roman; Fears, Kenan P.; Eichhorn, Bryan W.; Kuklja, Maija M.; Bluhm, Hendrik

doi:10.1007/s11244-018-1062-7

Cited by 9 publications

(10 citation statements)

References 34 publications

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“…Some metal oxides readily adsorb and decompose toxic agents, 11,13 whereas other oxides can effectively interact with toxins only in the presence of surface defects or surface hydroxyls. 7,12 Metal−organic frameworks 21−24 were proposed as potential filter materials because of their catalytic properties. Results of recent publications also indicate strong effect of molecular structure on decomposition mechanisms of organophosphorus compounds on metal oxide surfaces.…”

Section: Introductionmentioning

confidence: 99%

“…Over the last three decades, numerous experimental and theoretical studies were carried out to study atomistic interactions of organophosphorus CWAs and their model compounds with metal oxides. − These studies show that the interaction of simulant compounds with metal oxide surfaces depends on many factors, including a chemical composition, oxidation state of metal atoms, surface structure, and the presence of surface defects, water, and contaminants. Some metal oxides readily adsorb and decompose toxic agents, , whereas other oxides can effectively interact with toxins only in the presence of surface defects or surface hydroxyls. , Metal–organic frameworks − were proposed as potential filter materials because of their catalytic properties. Results of recent publications also indicate strong effect of molecular structure on decomposition mechanisms of organophosphorus compounds on metal oxide surfaces. , …”

Section: Introductionmentioning

confidence: 99%

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Degradation of Fatal Toxic Nerve Agents on Dry TiO₂

Tsyshevsky

McEntee

Durke

et al. 2020

ACS Appl. Mater. Interfaces

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Despite a recent dramatically increased risk of using chemical warfare agents in chemical attacks and assassinations, fundamental interactions of toxic chemicals with other materials are poorly understood, and micromechanisms of their chemical degradation are yet to be established. This represents an outstanding challenge in both fundamental science and practical applications in combat against chemical weapons. One of the most versatile and multifunctional oxides, TiO 2 , has been suggested as a promising material to quickly adsorb and effectively destroy toxins. In this paper, we explore how sarin (also known as GB) adsorbs and decomposes on dry nanoparticles of TiO 2 anatase and rutile phases. We found that both anatase and rutile readily adsorb sarin gas molecules because of a strong electrostatic attraction between the phosphoryl oxygen and surface titanium atoms. The sarin decomposition most likely proceeds via a propene elimination; however, the reaction is exothermic on the rutile (110) surface and endothermic on the anatase (101) surface. High energy barriers suggest that sarin would hardly decompose on pristine dry surfaces of TiO 2 , and degradation reactions can be triggered by defects or contaminants under realistic operational conditions.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Degradation of Fatal Toxic Nerve Agents on Dry TiO₂

Tsyshevsky

McEntee

Durke

et al. 2020

ACS Appl. Mater. Interfaces

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“…This is especially the case for organophosphonates that are used as chemical warfare agents (CWAs) because they are released under ambient conditions. 1 Dimethyl methylphosphonate (DMMP) is often used as a model for one common and highly toxic agent, sarin; [1][2] thus providing insight into the elementary steps that can lead to decomposition. Additionally, the environmental chemistry of organophosphonates 3 including DMMP is of broad interest because many pesticides are based on the organophosponate structural motif 2 , including the controversial, potentially carcinogenic glyphosate.…”

Section: Introductionmentioning

confidence: 99%

Facile Decomposition of Organophosphonates by Dual Lewis Sites on a Fe₃O₄(111) Film

Walenta

Tesvara

et al. 2020

J. Phys. Chem. C

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Dimethyl methylphosphonate (DMMP) is used as a simulant for toxic nerve agents and pesticides, rendering the understanding of surface chemistry requisite to design effective materials for organophosphonate (catalytic) decomposition at room temperature. In this work, DMMP surface chemistry is studied on an iron oxide surface in a very well-defined environment using temperature-programmed reaction, isotopic labeling, scanning tunneling microscopy, X-ray photoelectron spectroscopy, and density functional theory. DMMP, (CH 3 O) 2 P(O)(CH 3 ), dissociates to yield methoxy and methyl methylphosphonate, (CH 3 O)-P(O) 2 (CH 3 ), on the surface at room temperature. At higher temperatures, dimethyl ether is formed via intramolecular reaction, followed by the formation of formaldehyde and methanol from adsorbed methoxy decomposition during temperature-programmed reaction. Ultimately, stochiometric combustion at 870 K produces CO, H 2 CO, and CO 2 via reaction with lattice oxygen, with PO x remaining on the surface. Excess oxygen from the bulk is required to drive these higher temperature pathways. Neither hydrolysis nor a photoreaction is observed, when exposing the adsorbed DMMP to water or light above the band gap, respectively. No evolution of P-containing species is detected, indicating efficient trapping of this contaminant. The activity for DMMP decomposition at room temperature is reduced by the accumulation of PO x . However, a significant amount of reaction persists after multiple temperature-programmed reaction experiments.

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“…The same model surface containing an O vac and hydroxyl groups approximates the experimental surface characterized with XPS. 56 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, 57 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 4, and the corresponding energies are listed in Table 1.…”

Section: ■ Results and Discussionmentioning

confidence: 96%

“…The NO 2 adsorption and decomposition on the most stable MoO 3 (010) surface were modeled with DFT. 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.…”

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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Coupling Ambient Pressure X-ray Photoelectron Spectroscopy with Density Functional Theory to Study Complex Surface Chemistry and Catalysis

Cited by 9 publications

References 34 publications

Degradation of Fatal Toxic Nerve Agents on Dry TiO₂

Degradation of Fatal Toxic Nerve Agents on Dry TiO₂

Facile Decomposition of Organophosphonates by Dual Lewis Sites on a Fe₃O₄(111) Film

NO₂ Interactions with MoO₃ and CuO at Atmospherically Relevant Pressures

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Coupling Ambient Pressure X-ray Photoelectron Spectroscopy with Density Functional Theory to Study Complex Surface Chemistry and Catalysis

Cited by 9 publications

References 34 publications

Degradation of Fatal Toxic Nerve Agents on Dry TiO2

Degradation of Fatal Toxic Nerve Agents on Dry TiO2

Facile Decomposition of Organophosphonates by Dual Lewis Sites on a Fe3O4(111) Film

NO2 Interactions with MoO3 and CuO at Atmospherically Relevant Pressures

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Degradation of Fatal Toxic Nerve Agents on Dry TiO₂

Degradation of Fatal Toxic Nerve Agents on Dry TiO₂

Facile Decomposition of Organophosphonates by Dual Lewis Sites on a Fe₃O₄(111) Film

NO₂ Interactions with MoO₃ and CuO at Atmospherically Relevant Pressures