Surface Chemistry of Isopropoxy Tetramethyl Dioxaborolane on Cu(111)

Miller, Brendan; Furlong, Octavio Javier

doi:10.1021/la300276q

Cited by 7 publications

(11 citation statements)

References 27 publications

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“…As shown in Figure 7 with dark circles, the DFT calculations and chosen prefactor typically overestimate desorption temperatures by about 41 K. The linear correlation suggests that DFT calculations are reliable for obtaining catalytic trends. Furthermore, we extrapolate our ethanol results with the trend of 0.18 eV/ CH 2 to predict experimental TPD temperatures for isopropanol and acetone 48 desorption, as well as 1-butanol, butyraldehyde, crotyl alcohol, and crotanaldehyde. 49 For these predictions, we use the Redhead equation as above with the experimental heating rates.…”

Section: ■ Surface Reactivitymentioning

confidence: 99%

Anhydrous Methanol and Ethanol Dehydrogenation at Cu(111) Step Edges

et al. 2018

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Oxidative methanol dehydrogenation is a major industrial reaction with global formaldehyde production exceeding 30 million tonnes per year. Unfortunately, oxidative dehydrogenation produces water–aldehyde mixtures that require subsequent distillation. Anhydrous alcohol dehydrogenation is a promising alternative that produces H2 instead of water. Pursuant to recent experimental work showing that highly stepped Cu(111) surfaces exhibit anhydrous dehydrogenation activity, we present first-principles density functional theory calculations for methanol and ethanol dehydrogenation at Cu(111) step edges to provide an atomistic understanding of the catalytic mechanism; these sites stabilize all intermediates while reducing activation energies. We find that van der Waals contributions to the energy account for more than 50% of adsorption energies, and their inclusion is essential in achieving good agreement with experimental desorption temperatures. Furthermore, vibrational zero-point energy corrections significantly reduce the activation energy for all reaction steps considered here. Hydrogen bonding among ethanol intermediates at step edges is weakened by geometric frustration. These insights lead us to propose several suggestions for further research on undercoordinated Cu sites as anhydrous alcohol dehydrogenation catalysts.

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Section: ■ Surface Reactivitymentioning

confidence: 99%

Anhydrous Methanol and Ethanol Dehydrogenation at Cu(111) Step Edges

et al. 2018

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“…In this case, the rate of the thermal reaction is tribologically accelerated so that it occurs at room temperature much lower than the ~ 450 K at which it thermally decomposes. Similar strategies have been used to demonstrate that the tribochemistry of borate esters depends on its initial thermal surface reaction pathways [22,23], and for identifying the tribochemical reactions of phosphite esters [24]. The thermal surface reaction pathways identified in the absence of sliding provided a basis for understanding the tribochemical reactions.…”

Section: Introductionmentioning

confidence: 98%

Inducing High-Energy-Barrier Tribochemical Reaction Pathways; Acetic Acid Decomposition on Copper

2021

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The surface tribological chemistry of acetic acid on copper is studied using an ultrahigh vacuum tribometer, supplemented by first-principles density functional theory calculations of the surface structure and reaction pathways. Acetic acid forms η 2 -acetate species on bridge sites at room temperature as identified by reflection-absorption infrared spectroscopy. Rubbing the surface with a tungsten carbide ball reduces the amount of carbon and oxygen in the rubbed region at the same rates to leave some carbon and oxygen on the surface. This is different from the thermal decomposition pathway, where heating to ~ 580 K removes all oxygen, but leave a small amount of carbon on the surface. It is postulated that this arises because sliding along a direction aligned within the plane of the adsorbed acetate species can induce a high-energy-barrier pathway in which the η 2 -acetate tilts to form an η 1 -acetate that can react to form a bent CO 2 δ− species that decomposes to evolve carbon monoxide and deposit atomic oxygen on the surface. Repeated acetic acid dosing and rubbing reduces the total amount of acetic acid that can adsorb on the surface by ~ 50% after ~ 4 cycles, resulting is a stable, low-friction film. At this point, the adsorbed acetic acid is completely tribochemically removed. This suggests that adsorbed acetic acid can form a selfhealing film in which any wear of the low-friction film will then allow it to be replenished by shear-induced decomposition of adsorbed acetate species.

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“…The boron-containing intermediate also reacts to form acetone (118 °C) and 2,3-dimethyl-2-butene (91 °C), leaving B and BO x on the surface, respectively. 4…”

Section: Thermal Decomposition Of Itdb On Tio2mentioning

confidence: 99%

“…Moreover, the calculated vibrational frequencies (1000–1500 cm –1 ) of the dissociated ITDB agree with the 200 °C spectrum of ITDB/TiO 2 (Figure a). On Cu(111), ITDB is suggested to decompose primarily by B–O bond scission, forming two surface intermediates of [−OCH(CH 3 ) 2 ] and [−B(OC(CH 3 ) 2 –C(CH 3 ) 2 O)] . The isopropoxy continuously reacts on the surface and generates acetone at 54 °C.…”

Section: Thermal Decomposition Of Itdb On Tio2mentioning

confidence: 99%

“…Recently, the tribological properties of isopropoxy tetramethyl dioxaborolane (ITDB), with the structure of [B(OCH(CH 3 ) 2 )(OC(CH 3 ) 2 (CH 3 ) 2 CO)] shown in Scheme S1, on copper surfaces have been investigated, which is related to the lubrication of a sliding Cu (s) –Cu (s) contact in an electric rotor and to the molecular structure tribological chemistry. , In addition to the usage for forming tribofilms, trialkyl borates have been employed as a boron source in preparation of boron-doped TiO 2 materials to study their photoactivities, using a sol–gel method or via thermal decomposition over existing TiO 2 . − Zhang et al used Ti(OC 4 H 9 ) 4 and B(OC 4 H 9 ) 3 as the starting compounds to prepare boron-doped TiO 2 by the sol–gel method . It was found that this photocatalyst could decompose methyl orange under UV irradiation.…”

Section: Introductionmentioning

confidence: 99%

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Isopropoxy Tetramethyl Dioxaborolane on TiO₂: Reaction Pathway and Formation of a Visible-Light-Sensitive Photocatalyst

Lin

Lai

et al. 2019

ACS Omega

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Borate toxicity is a concern in agriculture since a high level of borates may likely exist in irrigation water systems. In this research, transmission infrared spectroscopy and X-ray photoelectron spectroscopy are employed to study the thermal and photochemical reactions of isopropoxy tetramethyl dioxaborolane (ITDB) on TiO2, with the aid of density functional theory calculations. In addition, the possibility for the formation of a boron-modified TiO2 (B/TiO2) surface, using ITDB as the boron source, is explored and the photocatalytic activity of the B/TiO2 is tested. After adsorption of ITDB on TiO2 at 35 °C and heating the surface to a temperature higher than ∼200 °C in a vacuum, the surface is found to be covered with both the organic components of OC(CH3)2–C(CH3)2O and OCH(CH3)2 and the inorganic components of (TiO2)BO and Ti–B–O. The organic intermediates can be further thermally transformed into pinacolone and acetone; however, the inorganic parts exist at 400 °C, forming a boron-modified surface. The thermal decomposition of ITDB is proposed to be initiated by breaking one B–O bond, forming −OC(CH3)2–C(CH3)2O–B–OCH(CH3)2 on the surface. In the case of photoreaction, the ITDB on TiO2 decomposes under photoirradiation at 325 nm to form acetone. The boron-modified TiO2 surface can absorb visible light, likely due to the presence of new states in the band gap, and shows a photocatalytical activity in degrading methylene blue, under 500 nm irradiation in air.

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Surface Chemistry of Isopropoxy Tetramethyl Dioxaborolane on Cu(111)

Cited by 7 publications

References 27 publications

Anhydrous Methanol and Ethanol Dehydrogenation at Cu(111) Step Edges

Anhydrous Methanol and Ethanol Dehydrogenation at Cu(111) Step Edges

Inducing High-Energy-Barrier Tribochemical Reaction Pathways; Acetic Acid Decomposition on Copper

Isopropoxy Tetramethyl Dioxaborolane on TiO₂: Reaction Pathway and Formation of a Visible-Light-Sensitive Photocatalyst

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Surface Chemistry of Isopropoxy Tetramethyl Dioxaborolane on Cu(111)

Cited by 7 publications

References 27 publications

Anhydrous Methanol and Ethanol Dehydrogenation at Cu(111) Step Edges

Anhydrous Methanol and Ethanol Dehydrogenation at Cu(111) Step Edges

Inducing High-Energy-Barrier Tribochemical Reaction Pathways; Acetic Acid Decomposition on Copper

Isopropoxy Tetramethyl Dioxaborolane on TiO2: Reaction Pathway and Formation of a Visible-Light-Sensitive Photocatalyst

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Isopropoxy Tetramethyl Dioxaborolane on TiO₂: Reaction Pathway and Formation of a Visible-Light-Sensitive Photocatalyst