Probing ensemble effects in surface reactions. 4. Cyclopentene adsorption on clean and bismuth-covered platinum(111)

Henn, F. C.; Dalton, Penni J.; Campbell, Charles T.

doi:10.1021/j100339a059

Cited by 38 publications

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“…Rodriguez and Campbell, and Henn et al [53,54] find that the activation energy for the dehydrogenation of c-C 5 H 8 to c-C 5 H 5 on Pt(1 1 1) (13.3 kcal/mol) is very similar to the activation energy for the conversion of c-C 6 H 12 to benzene on the same metal (13.4 kcal/mol). This similarity is consistent with the fact that the C-H bonds being broken in each case are for sp 3 -hybridized carbons.…”

Section: Resultsmentioning

confidence: 88%

The adsorption of methylcyclopentane on Pt(111)

et al. 2004

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Section: Resultsmentioning

confidence: 88%

The adsorption of methylcyclopentane on Pt(111)

et al. 2004

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“…For example, dehydrogenation for MeCp on Pt(111) has been shown by Morales and Zaera to occur above 350 K. 58 Similar studies for other unsaturated cyclic hydrocarbons have been performed, finding similar temperature thresholds for dehydrogenation. 56 , 59 These dehydrogenation reactions do not directly show up during ALD (for example, as a gas-phase reaction product) but they do play a key role in the formation of CH 4 as this reaction is the most likely source of H(ads) required for the hydrogenation reactions discussed earlier and could contribute to the self-limiting nature of the ALD reactions.…”

Section: Discussionmentioning

confidence: 99%

Surface Chemistry during Atomic Layer Deposition of Pt Studied with Vibrational Sum-Frequency Generation

2022

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A detailed understanding of the growth of noble metals by atomic layer deposition (ALD) is key for various applications of these materials in catalysis and nanoelectronics. The Pt ALD process using MeCpPtMe 3 and O 2 gas as reactants serves as a model system for the ALD processes of noble metals in general. The surface chemistry of this process was studied by in situ vibrational broadband sum-frequency generation (BB-SFG) spectroscopy, and the results are placed in the context of a literature overview of the reaction mechanism. The BB-SFG experiments provided direct evidence for the presence of CH 3 groups on the Pt surface after precursor chemisorption at 250 °C. Strong evidence was found for the presence of a C=C containing complex ( e.g ., the form of Cp species) and for partial dehydrogenation of the surface species during the precursor half-cycle. The reaction kinetics of the precursor half-cycle were followed at 250 °C, showing that the C=C coverage saturated before the saturation of CH 3 . This complex behavior points to the competition of multiple surface reactions, also reflected in the temperature dependence of the reaction mechanism. The CH 3 saturation coverage decreased significantly with temperature, while the C=C coverage remained constant after precursor chemisorption on the Pt surface for temperatures from 80 to 300 °C. These SFG results have resulted in a better understanding of the Pt ALD process and also highlight the surface chemistry during thin-film growth as a promising field of study for the BB-SFG community.

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“…This suggests that low Bi coverage may substantially decrease the adsorption energy (desorption rate) of benzene, thus calling into question the ensemble size requirements reported in. [53][54][55][56] Direct measurements of benzene adsorption energies in the presence of Bi would be required to confirm this.…”

Section: Discussionmentioning

confidence: 99%

“…[53][54][55][56] There, we used low coverages of coadsorbed bismuth atoms to block Pt sites, and quantified the resulting decrease in dehydrogenation rate as a function of Bi coverage. By fitting the data to a kinetic model, we were able to determine the number of unoccupied Pt surface atoms needed for dehydrogenation.…”

Section: Introductionmentioning

confidence: 99%

Calorimetric Measurement of the Heat of Adsorption of Benzene on Pt(111)

et al. 2004

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The heat of adsorption of benzene on clean Pt(111) at 300 K is measured calorimetrically and found to decrease with coverage (θ) as (197 -48θ -83θ 2 ) kJ/mol. Saturation coverage (θ ) 1.0) is 2.3 × 10 14 molecules/cm 2 . Sticking probabilities of benzene on Pt(111) were measured by mass spectrometry, giving an initial value of 0.97 and showing Kisliuk-type behavior with increasing coverage that implies there is a precursor to sticking with a ratio of its hopping rate to its desorption rate of ∼28. Benzene adsorbs transiently on the benzene-saturated surface at 300 K with a trapping probability of 0.90 and a heat of adsorption of 63-73 kJ/mol.

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Probing ensemble effects in surface reactions. 4. Cyclopentene adsorption on clean and bismuth-covered platinum(111)

Cited by 38 publications

References 0 publications

The adsorption of methylcyclopentane on Pt(111)

The adsorption of methylcyclopentane on Pt(111)

Surface Chemistry during Atomic Layer Deposition of Pt Studied with Vibrational Sum-Frequency Generation

Calorimetric Measurement of the Heat of Adsorption of Benzene on Pt(111)

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