P-078

Vladislav B. Ivaništševa,b

vladislav.ivanistsev@ut.ee

Iuliia V. Voroshylovac

aInstitute of Chemistry, University of Tartu, Tartu 50411, Estonia

bDepartment of Chemistry, University of Latvia, Jelgavas iela 1, LV-1004 Riga, Latvia

c3LAQV@REQUIMTE, Faculdade de Ciências, Universidade do Porto, Departamento de Química e Bioquímica, Rua do Campo Alegre, 4169-007, Porto, Portugal

Establishing electrochemical and electrophysical potentials that govern processes at electrified interfaces

In electrochemistry, all processes happen within the electrochemical window. Herewith, phenomena like anomalous capacitance and superlubricity are, in essence, electrophysical as they are driven by non-faradaic processes such as steric packing and charge screening.1,2 Such interfacial phenomena are common for concentrated electrolytes like ionic liquids.3,4 Understanding steric packing and charge screening at such complex interfaces is possible with computer simulations with selectively disabled chemical reactivity.

Using computer simulations,5–7 we identified two complementary reference potentials – the potential of monolayer charge (PMC) and the potential of saturation charge (PSC) – to expand the traditional electrochemical potential scale from the potential of zero charge (PZC) to the edges of electrochemical window. These charge-oriented potentials form a coherent scale for interpreting charge screening and structure evolution at interfaces upon applying potential. The proposed scale explains key interfacial phenomena such as hysteresis in capacitance and overpotential in deposition (in ionic liquids), linking them to the saturation of the contact layer.

By integrating simulation results with conceptual analysis, this presentation connects saturation with emergent properties, including friction, capacitance, and transport-limited reaction rates. We discuss strategies for analyzing simulations in this context and outline their relevance to experimental observations. The goal is to demonstrate how electrophysical concepts can complement electrochemical understanding, particularly in complex, highly concentrated systems.

References

1 J. Wu, Understanding the Electric Double-Layer Structure, Capacitance, and Charging Dynamics, Chem. Rev., 2022, 122, 10821–10859.

2 J. P. de Souza, Z. A. H. Goodwin, M. McEldrew, A. A. Kornyshev and M. Z. Bazant, Interfacial Layering in the Electric Double Layer of Ionic Liquids, Phys. Rev. Lett., 2020, 125, 116001.

3 A. A. Kornyshev, Double-Layer in Ionic Liquids: Paradigm Change?, J. Phys. Chem. B, 2007, 111, 5545–5557.

4 M. Z. Bazant, B. D. Storey and A. A. Kornyshev, Double Layer in Ionic Liquids: Overscreening versus Crowding, Phys. Rev. Lett., 2011, 106, 046102.

5 I. V. Voroshylova, H. Ers, V. Koverga, B. Docampo-Álvarez, P. Pikma, V. B. Ivaništšev and M. N. D. S. Cordeiro, Ionic liquid–metal interface: The origins of capacitance peaks, Electrochimica Acta, 2021, 379, 138148.

6 H. Ers, I. V. Voroshylova, P. Pikma and V. B. Ivaništšev, Double layer in ionic liquids: Temperature effect and bilayer model, J. Mol. Liq., 2022, 363, 119747.

7 K. Karu, E.R. Nerut, X. Tao, S.A. Kislenko, K. Pohako-Esko, I.V. Voroshylova, V.B. Ivaništšev, Ionic liquid–electrode interface: Classification of ions, saturation of layers, and structure-determined potentials, Electrochimica Acta 503 (2024) 144829..

Acknowledgement

This presentation is supported by the Estonian Ministry of Education and Research (TK210) and the Estonian Research Council (grant STP52).