Regensburg 2022 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 31: Solid-Liquid Interfaces 3: Reactions and Electrochemistry
O 31.6: Vortrag
Dienstag, 6. September 2022, 12:00–12:15, S054
Understanding the Interfacial Capacitance of 2D Materials in an Implicit Water Environment — •Hedda Oschinski1,2, Nicolas G. Hörmann1, and Karsten Reuter1 — 1Fritz-Haber-Institut der Max-Planck-Gesellschaft, Berlin, Germany — 2Technical University of Munich, Germany
The interfacial capacitance (C) is a central quantity in electrochemistry. For metal electrodes, C is dominated by the double layer capacitance that derives from the potential drop in the solvent. However, the finite density of states (DOS) in semiconducting 2D electrodes alters the picture and leads to a vanishing C around the point of zero charge. This entails a challenge in describing the energy-potential relation and the connected field effects when considering adsorbates.
To explore this challenge, we study the interfacial capacitance for 2D metal halides MX2, using density-functional theory in a continuum solvent environment. We break down C into a DOS-filling-related quantum capacitance and the double layer capacitance. Our analysis demonstrates that such a separation into individual components is not straightforward. Nevertheless, the qualitative behavior of C can be rationalized, making this study a first step towards better understanding of 2D, in particular semiconducting, electrodes.