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Coupling of Surface Chemistry and Electric Double Layer at TiO2 Electrochemical Interfaces


Zhang, Chao; Hutter, Jürg; Sprik, Michiel (2019). Coupling of Surface Chemistry and Electric Double Layer at TiO2 Electrochemical Interfaces. Journal of Physical Chemistry Letters, 10(14):3871-3876.

Abstract

Surfaces of metal oxides at working conditions are usually electrified because of the acid–base chemistry. The charged interface compensated with counterions forms the so-called electric double layer. The coupling of surface chemistry and the electric double layer is considered to be crucial but is poorly understood because of the lack of information at the atomistic scale. Here, we used the latest development in density functional theory-based finite-field molecular dynamics simulation to investigate the pH dependence of the Helmholtz capacitance at electrified rutile TiO2(110)–NaCl electrolyte interfaces. It is found that, because of competing forces from surface adsorption and from the electric double layer, water molecules have a stronger structural fluctuation at high pH, and this leads to a much larger capacitance. It is also seen that interfacial proton transfers at low pH increase significantly the capacitance value. These findings elucidate the microscopic origin of the same trend observed in titration experiments.

Abstract

Surfaces of metal oxides at working conditions are usually electrified because of the acid–base chemistry. The charged interface compensated with counterions forms the so-called electric double layer. The coupling of surface chemistry and the electric double layer is considered to be crucial but is poorly understood because of the lack of information at the atomistic scale. Here, we used the latest development in density functional theory-based finite-field molecular dynamics simulation to investigate the pH dependence of the Helmholtz capacitance at electrified rutile TiO2(110)–NaCl electrolyte interfaces. It is found that, because of competing forces from surface adsorption and from the electric double layer, water molecules have a stronger structural fluctuation at high pH, and this leads to a much larger capacitance. It is also seen that interfacial proton transfers at low pH increase significantly the capacitance value. These findings elucidate the microscopic origin of the same trend observed in titration experiments.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:07 Faculty of Science > Department of Chemistry
Dewey Decimal Classification:540 Chemistry
Uncontrolled Keywords:General Materials Science
Language:English
Date:18 July 2019
Deposited On:22 Nov 2019 16:03
Last Modified:22 Nov 2019 16:03
Publisher:American Chemical Society (ACS)
ISSN:1948-7185
OA Status:Closed
Publisher DOI:https://doi.org/10.1021/acs.jpclett.9b01355

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