Implications of the Fractional Charge of Hydroxide at the Electrochemical Interface

Joseph A. Gauthier, Leanne D. Chen, Michal Bajdich, Karen Chan*

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

Rational design of materials that efficiently convert electrical energy into chemical bonds will ultimately depend on a thorough understanding of the electrochemical interface 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.
Original languageEnglish
JournalPhysical Chemistry Chemical Physics
Volume22
Issue number13
Pages (from-to)6964-6969
ISSN1463-9076
Publication statusPublished - 2020

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