Ionic liquid-metal interface: The origins of capacitance peaks

• Type: Article in International Scientific Journal
• Date: 2021

Authors

Voroshylova, IV (Author) FCUP; Ers, H (Author) Other; Koverga, V (Author) Other; Docampo Alvarez, B (Author) Other; Pikma, P (Author) Other; Ivanistsev, VB (Author) Other; Natalia N D S Cordeiro (Author) FCUP

Journal

Title: Electrochimica Acta

Vol. 379

ISSN: 0013-4686

Publisher: Elsevier

Indexing

ISI Web of Knowledge - 10 Citations

Scopus - 12 Citations

Other information

Authenticus ID: P-00T-Q83

DOI: 10.1016/j.electacta.2021.138148

Abstract (EN): The complex nature of electrode charge screening is well-known for ionic liquids (ILs). Due to strong ionion correlations, these electrolytes form a distinctive layered structure at interfaces. Variations in electrode potential cause structural changes that are reflected in a peculiar shape of differential capacitance-potential dependence with characteristic peaks. Although the differential capacitance for various ILs in conjunction with metal electrodes accessed via molecular dynamics (MD) simulations has been reported in the literature, retrieving a capacitance-potential curve, C(U), from the MD trajectories is not a trivial task. In this work, we present the results of the MD simulations of the IL 1-butyl-3-methylimidazolium hexafluorophosphate at a single-crystalline Au (100) surface. The discussion focuses on the simulation data treatment for C(U) curve fitting. It is shown that the resulting C strongly depends on the fitting method used. Four capacitance peaks and three structural reorganization types were identified in the studied system. With the help of a semi-quantitative approach in the framework of the original bilayer model of electric double layer (EDL), it is argued that the ions' reorientation is in the origin of the capacitance peaks. Also, it is shown that under the conditions of this study, the multilayer structure, characteristic of EDL in ILs on the whole, is far from the "lattice saturation" regime. The multilayer structure possesses a steric packing effect that impedes structural changes, decreasing the capacitance.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 11