Berlin 2024 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 96: Solid-Liquid Interfaces IV: Reactions and Electrochemistry
O 96.8: Vortrag
Donnerstag, 21. März 2024, 17:00–17:15, TC 006
Approximating Grand-Canonical Energetics of Electrified Semiconductor-Electrolyte Interfaces – A Benchmark Study — •Hedda Oschinski1,2, Karsten Reuter1,2, and Nicolas G. Hörmann1 — 1Fritz-Haber-Institut der MPG, Berlin — 2Technische Universität München
Computational studies of the electrosorption of adsorbates centrally target the grand canonical (GC) energetics Gs(φE) with respect to an applied potential φE. For metal electrodes, Gs(φE) can be well described by a parabolic form that incorporates the interfacial capacitance C at the potential of zero charge. Unfortunately, for semiconductors (SC), this appealing approximation breaks down due to the existence of the band gap. Here, we propose a simple extension that explicitly incorporates the electrode density of states (DOS) and thus allows to describe C for both metals and SCs. For SCs, C is thereby partitioned into a DOS capacitance and a solution capacitance using a straightforward DOS shift picture that combines the filling of electronic states with the shift of the electrostatic potential drop across the electrode-electrolyte interface. Using density-functional theory calculations in an implicit solvation environment, we benchmark the model for a set of conducting and semiconducting/insulating 2D materials. The GC energetics is reliably reproduced across the entire materials space, with only minor deviations but at a fraction of the computational cost. The analysis underlines the importance of the position of the band gap and the response of the solution, in line with classical macroscopic ideas of semiconductor electrochemistry.
Keywords: semiconductor; capacitance; 2D material; implicit solvation; electrocatalysis