The electric double layer at a rutile TiO2 water interface using density functional theory based molecular dynamics simulation

J Cheng, M Sprik

Research output: Contribution to journalArticle

37 Citations (Scopus)

Abstract

A fully atomistic model of a compact electric double layer at the rutile TiO2(1 1 0)-water interface is constructed by adding protons to bridging oxygens or removing them from H2O molecules adsorbed on terminal metal cation sites. The surface charge is compensated by F− or Na+ counter ions in outer as well as inner sphere coordination. For each of the protonation states the energy of the TiO2 conduction band minimum is determined relative to the standard hydrogen electrode by computing the free energy for the combined insertion of an electron in the solid and a proton in solution away from the double layer using density functional theory based molecular dynamics methods. Interpreted as electrode potentials, this gives an estimate of the capacitance which is compared to the capacitance obtained from the difference in the average electrostatic potentials in the solid and aqueous phase. When aligned at the point of zero charge these two methods lead to almost identical potential-charge profiles. We find that inner sphere complexes have a slightly larger capacitance (0.4 F m−2) compared to outer sphere complexes (0.3 F m−2).
Original languageEnglish
Article number244108
JournalJournal of Physics: Condensed Matter
Volume26
Issue number24
DOIs
Publication statusPublished - 18 Jun 2014

Fingerprint

rutile
Interfaces (computer)
Density functional theory
Molecular dynamics
Capacitance
capacitance
molecular dynamics
density functional theory
Protons
Water
Computer simulation
water
Electrodes
Radiation counters
electrodes
protons
simulation
Protonation
Surface charge
Conduction bands

Cite this

The electric double layer at a rutile TiO2 water interface using density functional theory based molecular dynamics simulation. / Cheng, J; Sprik, M.

In: Journal of Physics: Condensed Matter, Vol. 26, No. 24, 244108 , 18.06.2014.

Research output: Contribution to journalArticle

@article{18858b03864d4a6c9673969ace7da503,
title = "The electric double layer at a rutile TiO2 water interface using density functional theory based molecular dynamics simulation",
abstract = "A fully atomistic model of a compact electric double layer at the rutile TiO2(1 1 0)-water interface is constructed by adding protons to bridging oxygens or removing them from H2O molecules adsorbed on terminal metal cation sites. The surface charge is compensated by F− or Na+ counter ions in outer as well as inner sphere coordination. For each of the protonation states the energy of the TiO2 conduction band minimum is determined relative to the standard hydrogen electrode by computing the free energy for the combined insertion of an electron in the solid and a proton in solution away from the double layer using density functional theory based molecular dynamics methods. Interpreted as electrode potentials, this gives an estimate of the capacitance which is compared to the capacitance obtained from the difference in the average electrostatic potentials in the solid and aqueous phase. When aligned at the point of zero charge these two methods lead to almost identical potential-charge profiles. We find that inner sphere complexes have a slightly larger capacitance (0.4 F m−2) compared to outer sphere complexes (0.3 F m−2).",
author = "J Cheng and M Sprik",
note = "Acknowledgments JC is grateful for financial support from Emmanuel College Cambridge and the Engineering and Physical Sciences Research Council (EPSRC) of the United Kingdom. We also acknowledge support from the UKCP consortium for access to HECToR, the UK's high-end computing resource funded by the Research Councils.",
year = "2014",
month = "6",
day = "18",
doi = "10.1088/0953-8984/26/24/244108",
language = "English",
volume = "26",
journal = "Journal of Physics: Condensed Matter",
issn = "0953-8984",
publisher = "IOP Publishing Ltd.",
number = "24",

}

TY - JOUR

T1 - The electric double layer at a rutile TiO2 water interface using density functional theory based molecular dynamics simulation

AU - Cheng, J

AU - Sprik, M

N1 - Acknowledgments JC is grateful for financial support from Emmanuel College Cambridge and the Engineering and Physical Sciences Research Council (EPSRC) of the United Kingdom. We also acknowledge support from the UKCP consortium for access to HECToR, the UK's high-end computing resource funded by the Research Councils.

PY - 2014/6/18

Y1 - 2014/6/18

N2 - A fully atomistic model of a compact electric double layer at the rutile TiO2(1 1 0)-water interface is constructed by adding protons to bridging oxygens or removing them from H2O molecules adsorbed on terminal metal cation sites. The surface charge is compensated by F− or Na+ counter ions in outer as well as inner sphere coordination. For each of the protonation states the energy of the TiO2 conduction band minimum is determined relative to the standard hydrogen electrode by computing the free energy for the combined insertion of an electron in the solid and a proton in solution away from the double layer using density functional theory based molecular dynamics methods. Interpreted as electrode potentials, this gives an estimate of the capacitance which is compared to the capacitance obtained from the difference in the average electrostatic potentials in the solid and aqueous phase. When aligned at the point of zero charge these two methods lead to almost identical potential-charge profiles. We find that inner sphere complexes have a slightly larger capacitance (0.4 F m−2) compared to outer sphere complexes (0.3 F m−2).

AB - A fully atomistic model of a compact electric double layer at the rutile TiO2(1 1 0)-water interface is constructed by adding protons to bridging oxygens or removing them from H2O molecules adsorbed on terminal metal cation sites. The surface charge is compensated by F− or Na+ counter ions in outer as well as inner sphere coordination. For each of the protonation states the energy of the TiO2 conduction band minimum is determined relative to the standard hydrogen electrode by computing the free energy for the combined insertion of an electron in the solid and a proton in solution away from the double layer using density functional theory based molecular dynamics methods. Interpreted as electrode potentials, this gives an estimate of the capacitance which is compared to the capacitance obtained from the difference in the average electrostatic potentials in the solid and aqueous phase. When aligned at the point of zero charge these two methods lead to almost identical potential-charge profiles. We find that inner sphere complexes have a slightly larger capacitance (0.4 F m−2) compared to outer sphere complexes (0.3 F m−2).

U2 - 10.1088/0953-8984/26/24/244108

DO - 10.1088/0953-8984/26/24/244108

M3 - Article

VL - 26

JO - Journal of Physics: Condensed Matter

JF - Journal of Physics: Condensed Matter

SN - 0953-8984

IS - 24

M1 - 244108

ER -