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Implications of the Fractional Charge of Hydroxide at the Electrochemical Interface

preprint
submitted on 21.08.2019, 14:44 and posted on 22.08.2019, 16:21 by Joseph Gauthier, Leanne D. Chen, Michal Bajdich, Karen Chan

Rational design of materials that efficiently convert electrical energy into chemical bonds will ultimately depend on a thorough understanding of the electrochemical inter- face at the atomic level. Towards this goal, the use of density functional theory (DFT) at the generalized gradient approximation (GGA) level has been applied widely in the past 15 years. In the calculation of electrochemical reaction energetics using GGA-DFT, it is frequently implicitly assumed that ions in the Helmholtz plane have unit charge. However, the ion charge is observed to be fractional near the interface through both a capacitor model and through Bader charge partitioning. In this work, we show that this spurious charge transfer can be effectively mitigated by continuum charging of the electrolyte. We then show that, similar to hydronium, the observed fractional charge of hydroxide is not due to a GGA level self-interaction error, as the partial charge is observed even when using hybrid level exchange-correlation functionals.

Funding

Energy Innovation Hub Renewal - Fuels from Sunlight

Basic Energy Sciences

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History

Email Address of Submitting Author

jgauth32@stanford.edu

Institution

Stanford University

Country

United States

ORCID For Submitting Author

0000-0001-9542-0988

Declaration of Conflict of Interest

No conflict of interest

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in Physical Chemistry Chemical Physics

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