Abstract
In this work, we theoretically study the differential capacitance of an aqueous electrolyte in contact with a planar electrode, using classical density functional theory, and show how this measurable quantity can be used as a probe to better understand the structure and composition of the electric double layer at play. Specifically, we show how small trace amounts of divalent ions can influence the differential capacitance greatly and also how small ions dominate its behavior for high electrode potentials. In this study, we consider primitive model electrolytes and not only use the standard definition of the differential capacitance but also derive a new expression from mechanical equilibrium in a planar geometry. This expression reveals explicitly that the first layer of ions near the charged surface is key to its understanding. Our insights might be used as a guide in experiments to better understand the electrolyte-electrode interface as well as the (composition of the) bulk electrolyte.
| Original language | English |
|---|---|
| Article number | 104702 |
| Pages (from-to) | 1-13 |
| Number of pages | 13 |
| Journal | Journal of Chemical Physics |
| Volume | 155 |
| Issue number | 10 |
| DOIs | |
| Publication status | Published - 14 Sept 2021 |
Bibliographical note
Funding Information:We thank Willem Boon for engaging discussions. This work was part of the D-ITP consortium, a program of the Netherlands Organisation for Scientific Research (NWO) that is funded by the Dutch Ministry of Education, Culture and Science (OCW). It also forms part of the NWO program “Datadriven science for smart and sustainable energy research,” with Project No. 16DDS014. The authors have no conflicts to disclose.
Publisher Copyright:
© 2021 Author(s).
Funding
We thank Willem Boon for engaging discussions. This work was part of the D-ITP consortium, a program of the Netherlands Organisation for Scientific Research (NWO) that is funded by the Dutch Ministry of Education, Culture and Science (OCW). It also forms part of the NWO program “Datadriven science for smart and sustainable energy research,” with Project No. 16DDS014. The authors have no conflicts to disclose.