Thermodynamics of Alkanethiol Self-Assembled Monolayer Assembly on Pd Surfaces

Gaurav Kumar, Timothy Van Cleve, Jiyun Park, Adri Van Duin, J. Will Medlin, Michael John Janik

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

We investigate the structure and binding energy of alkanethiolate self-assembled monolayers (SAMs) on Pd (111), Pd (100), and Pd (110) facets at different coverages. Dispersion-corrected density functional theory calculations are used to correlate the binding energy of alkanethiolates with alkyl chain length and coverage. The equilibrium coverage of thiolate layers strongly prefers 1/3 monolayer (ML) on the Pd (111) surface. The coverage of thiolates varies with chemical potential on Pd (100) and Pd (110), increasing from 1/3 to 1/2 ML on (100) and from 1/4 to 1/2 ML on (110) as the thiol chemical potential is increased. Higher coverages are driven by attractive dispersion interactions between the extended alkyl chains, such that transitions to higher coverages occur at lower thiol chemical potentials for longer chain thiolates. Stronger adsorption to the Pd (100) surface causes the equilibrium Wulff construction of Pd particles to take on a cubic shape upon saturation with thiols. The binding of H, O, and CO adsorbates is weakened as the thiolate coverage is increased, with saturation coverages causing unfavorable binding of O and CO on Pd (100) and weakened binding on other facets. Temperature-dependent CO diffuse reflectance infrared Fourier transform spectroscopy experiments are used to corroborate the weakened binding of CO in the presence of thiolate SAMs of varying surface density. Preliminary results of multiscale modeling efforts on the Pd-thiol system using a reactive force field, ReaxFF, are also discussed.

Original languageEnglish (US)
Pages (from-to)6346-6357
Number of pages12
JournalLangmuir
Volume34
Issue number22
DOIs
StatePublished - Jun 5 2018

Fingerprint

Chemical potential
Self assembled monolayers
Carbon Monoxide
Sulfhydryl Compounds
thiols
Monolayers
assembly
Thermodynamics
Binding energy
thermodynamics
flat surfaces
binding energy
Adsorbates
saturation
Chain length
Fourier transform infrared spectroscopy
Density functional theory
field theory (physics)
Adsorption
density functional theory

All Science Journal Classification (ASJC) codes

  • Materials Science(all)
  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Spectroscopy
  • Electrochemistry

Cite this

Kumar, Gaurav ; Van Cleve, Timothy ; Park, Jiyun ; Van Duin, Adri ; Medlin, J. Will ; Janik, Michael John. / Thermodynamics of Alkanethiol Self-Assembled Monolayer Assembly on Pd Surfaces. In: Langmuir. 2018 ; Vol. 34, No. 22. pp. 6346-6357.
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Thermodynamics of Alkanethiol Self-Assembled Monolayer Assembly on Pd Surfaces. / Kumar, Gaurav; Van Cleve, Timothy; Park, Jiyun; Van Duin, Adri; Medlin, J. Will; Janik, Michael John.

In: Langmuir, Vol. 34, No. 22, 05.06.2018, p. 6346-6357.

Research output: Contribution to journalArticle

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T1 - Thermodynamics of Alkanethiol Self-Assembled Monolayer Assembly on Pd Surfaces

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