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Thermodynamics and kinetics of CO and benzene adsorption on Pt(111) studied with pulsed molecular beams and microcalorimetry

Schießer, Alexander ; Hörtz, Peter ; Schäfer, Rolf (2023)
Thermodynamics and kinetics of CO and benzene adsorption on Pt(111) studied with pulsed molecular beams and microcalorimetry.
In: Surface Science, 2010, 604 (23-24)
doi: 10.26083/tuprints-00024246
Article, Secondary publication, Postprint

Abstract

The adsorption and desorption of the system CO/Pt(111) and C6H6/Pt(111) at 300 K has been investigated with a pulsed molecular beam method in combination with a microcalorimeter. For benzene the sticking probability has been measured in dependence of the coverage θ. For coverages θ > 0.8 transient adsorption is observed. From an analysis of the time-dependence of the molecular beam pulses the rate constant for desorption is determined to be 5.6 s− 1. With a precursor-mediated kinetic adsorption model this allows to obtain also the hopping rate constant of 95.5 s− 1. The measured adsorption enthalpies could be best described by (199 − 77θ − 51θ2) kJ/mol, in good agreement with the literature values. For CO on Pt(111) also transient adsorption has been observed for θ > 0.95 at 300 K. The kinetic analysis yields rate constants for desorption and hopping of 20 s−1 and 51 s−1, respectively. The heats of adsorption show a linear dependence on coverage (131 − 38θ) kJ/mol between 0 ≤ θ ≤ 0.3, which is consistent with the desorption data from the literature. For higher coverage (up to θ = 0.9ML) a slope of −63 kJ/mol describes the decrease of the differential heat of adsorption best. This result is only compatible with desorption experiments, if the pre-exponential factor decreases strongly at higher coverage. We found good agreement with recent quantum chemical calculations made for (θ = 0.5ML).

Item Type: Article
Erschienen: 2023
Creators: Schießer, Alexander ; Hörtz, Peter ; Schäfer, Rolf
Type of entry: Secondary publication
Title: Thermodynamics and kinetics of CO and benzene adsorption on Pt(111) studied with pulsed molecular beams and microcalorimetry
Language: English
Date: 2023
Place of Publication: Darmstadt
Year of primary publication: 2010
Publisher: Elsevier
Journal or Publication Title: Surface Science
Volume of the journal: 604
Issue Number: 23-24
DOI: 10.26083/tuprints-00024246
URL / URN: https://tuprints.ulb.tu-darmstadt.de/24246
Corresponding Links:
Origin: Secondary publication service
Abstract:

The adsorption and desorption of the system CO/Pt(111) and C6H6/Pt(111) at 300 K has been investigated with a pulsed molecular beam method in combination with a microcalorimeter. For benzene the sticking probability has been measured in dependence of the coverage θ. For coverages θ > 0.8 transient adsorption is observed. From an analysis of the time-dependence of the molecular beam pulses the rate constant for desorption is determined to be 5.6 s− 1. With a precursor-mediated kinetic adsorption model this allows to obtain also the hopping rate constant of 95.5 s− 1. The measured adsorption enthalpies could be best described by (199 − 77θ − 51θ2) kJ/mol, in good agreement with the literature values. For CO on Pt(111) also transient adsorption has been observed for θ > 0.95 at 300 K. The kinetic analysis yields rate constants for desorption and hopping of 20 s−1 and 51 s−1, respectively. The heats of adsorption show a linear dependence on coverage (131 − 38θ) kJ/mol between 0 ≤ θ ≤ 0.3, which is consistent with the desorption data from the literature. For higher coverage (up to θ = 0.9ML) a slope of −63 kJ/mol describes the decrease of the differential heat of adsorption best. This result is only compatible with desorption experiments, if the pre-exponential factor decreases strongly at higher coverage. We found good agreement with recent quantum chemical calculations made for (θ = 0.5ML).

Uncontrolled Keywords: Microcalorimetry, Sticking probability, Adsorption energies, Carbon monoxide, Benzene, Pt(111)
Status: Postprint
URN: urn:nbn:de:tuda-tuprints-242468
Classification DDC: 500 Science and mathematics > 540 Chemistry
Divisions: 07 Department of Chemistry
07 Department of Chemistry > Eduard Zintl-Institut > Fachgebiet Anorganische Chemie
07 Department of Chemistry > Eduard Zintl-Institut > Physical Chemistry
Date Deposited: 11 Jul 2023 07:15
Last Modified: 12 Jul 2023 05:53
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