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Understanding adsorption of organics on Pt(111) in the aqueous phase: insights from DFT based implicit solvent and statistical thermodynamics models

Understanding adsorption of organics on Pt(111) in the aqueous phase: insights from DFT based implicit solvent and statistical thermodynamics models
Understanding adsorption of organics on Pt(111) in the aqueous phase: insights from DFT based implicit solvent and statistical thermodynamics models
Adsorption of organics in the aqueous phase is an area which is experimentally difficult to measure, while computational techniques require extensive configurational sampling of the solvent and adsorbate. This is exceedingly computationally demanding, which excludes its routine use. If implicit solvent could be applied instead, this would dramatically reduce the computational cost as configurational sampling of solvent is not needed. Here, using statistical thermodynamic arguments and DFT calculations with implicit solvent models, we show that semiquantitative values for the free energy and entropy change of adsorption in the aqueous phase (ΔGadssolv and ΔSadssolv) for small organics can be calculated, for a range of coverages. We parametrize the soft sphere based solute dielectric cavity to an approximated free energy of solvation for a single Pt atom at the (111) facet, forming upper and lower bounds based on the entropy of water at the aqueous metal interface (ΔGsolv(Pt) = −4.35 to −7.18 kJ mol–1). This captures the decrease in ΔGadssolv compared to the free energy of adsorption in the vacuum phase (ΔGadsvac), while solvent models with electron density based cavities fail to do so. For a range of oxygenated aromatics, the adsorption energetics using horizontal gas phase geometries significantly overestimate ΔGadssolv compared to experiment by ∼100 kJ mol–1, but they agree with ab initio MD simulations using similar geometries. This suggests oxygenated aromatic compounds adsorb perpendicular to the metallic surface, while the ΔGadssolv for vertical geometries of furfural and cyclohexanol agree to within 20 kJ mol–1 of experimental studies. The proposed techniques provide an inexpensive toolset for validation and prediction of adsorption energetics on solvated metallic surfaces, which could be further validated by the future availability of more experimental measurements for the aqueous entropy/free energy of adsorption.
1549-9618
1849–1861
Bramley, Gabriel, Adrian
3ed28a08-44fe-4c51-bd9e-7a9309247c1b
Nguyen, Manh-Thuong
6ad86d09-8f27-4d61-90b6-4f76b912f299
Glezakou, Vassiliki-Alexandra
1252b310-9674-4b5d-95fb-5e45a44f3068
Rousseau, Roger
3588ba57-c98b-43bc-86cd-7be0191ba798
Skylaris, Chris-Kriton
8f593d13-3ace-4558-ba08-04e48211af61
Bramley, Gabriel, Adrian
3ed28a08-44fe-4c51-bd9e-7a9309247c1b
Nguyen, Manh-Thuong
6ad86d09-8f27-4d61-90b6-4f76b912f299
Glezakou, Vassiliki-Alexandra
1252b310-9674-4b5d-95fb-5e45a44f3068
Rousseau, Roger
3588ba57-c98b-43bc-86cd-7be0191ba798
Skylaris, Chris-Kriton
8f593d13-3ace-4558-ba08-04e48211af61

Bramley, Gabriel, Adrian, Nguyen, Manh-Thuong, Glezakou, Vassiliki-Alexandra, Rousseau, Roger and Skylaris, Chris-Kriton (2022) Understanding adsorption of organics on Pt(111) in the aqueous phase: insights from DFT based implicit solvent and statistical thermodynamics models. Journal of Chemical Theory and Computation, 18 (3), 1849–1861. (doi:10.1021/acs.jctc.1c00894).

Record type: Article

Abstract

Adsorption of organics in the aqueous phase is an area which is experimentally difficult to measure, while computational techniques require extensive configurational sampling of the solvent and adsorbate. This is exceedingly computationally demanding, which excludes its routine use. If implicit solvent could be applied instead, this would dramatically reduce the computational cost as configurational sampling of solvent is not needed. Here, using statistical thermodynamic arguments and DFT calculations with implicit solvent models, we show that semiquantitative values for the free energy and entropy change of adsorption in the aqueous phase (ΔGadssolv and ΔSadssolv) for small organics can be calculated, for a range of coverages. We parametrize the soft sphere based solute dielectric cavity to an approximated free energy of solvation for a single Pt atom at the (111) facet, forming upper and lower bounds based on the entropy of water at the aqueous metal interface (ΔGsolv(Pt) = −4.35 to −7.18 kJ mol–1). This captures the decrease in ΔGadssolv compared to the free energy of adsorption in the vacuum phase (ΔGadsvac), while solvent models with electron density based cavities fail to do so. For a range of oxygenated aromatics, the adsorption energetics using horizontal gas phase geometries significantly overestimate ΔGadssolv compared to experiment by ∼100 kJ mol–1, but they agree with ab initio MD simulations using similar geometries. This suggests oxygenated aromatic compounds adsorb perpendicular to the metallic surface, while the ΔGadssolv for vertical geometries of furfural and cyclohexanol agree to within 20 kJ mol–1 of experimental studies. The proposed techniques provide an inexpensive toolset for validation and prediction of adsorption energetics on solvated metallic surfaces, which could be further validated by the future availability of more experimental measurements for the aqueous entropy/free energy of adsorption.

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Accepted/In Press date: 31 January 2022
e-pub ahead of print date: 31 January 2022
Published date: 8 March 2022
Additional Information: Funding Information: V.-A.G., M.-T.N., and R.R. were supported by the U.S. Department of Energy (DOE), Office of Science, Office of Basic Energy Sciences (BES), Chemical Sciences, Geosciences, and Biosciences Division. Computer resources were provided by Research Computing at Pacific Northwest National Laboratory (PNNL) and the National Energy Research Scientific Computing Center (NERSC), a DOE Office of Science User Facility operated under Contract No. DE-AC02-05CH11231. PNNL is operated by Battelle for the U.S. Department of Energy under Contract No. DE-AC05-76RL01830. G.A.B. acknowledges support for his Ph.D. funding equally from EPSRC and BES. The authors acknowledge the use of the IRIDIS High Performance Computing Facility (IRIDIS 5) and associated support services at the University of Southampton in the completion of this work. We are grateful to the U.K. Materials and Molecular Modeling Hub (Young HPC) for computational resources, which is partially funded by EPSRC (EPSRC Grant No. EP/T022213/1), and to the UKCP consortium for access to the ARCHER2 supercomputer (EPSRC Grant No. EP/P022030/1). Publisher Copyright: © 2022 American Chemical Society. All rights reserved.

Identifiers

Local EPrints ID: 455337
URI: http://eprints.soton.ac.uk/id/eprint/455337
ISSN: 1549-9618
PURE UUID: 3432128b-5f3c-4d5b-a560-a813acbcfee6
ORCID for Chris-Kriton Skylaris: ORCID iD orcid.org/0000-0003-0258-3433

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Date deposited: 17 Mar 2022 17:33
Last modified: 31 Jan 2023 05:01

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Contributors

Author: Gabriel, Adrian Bramley
Author: Manh-Thuong Nguyen
Author: Vassiliki-Alexandra Glezakou
Author: Roger Rousseau

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