Simulating electrochemical systems by combining the finite field method with a constant potential electrode

Thomas Dufils (1) , Guillaume Jeanmairet (2) , Benjamin Rotenberg (3) , Michiel Sprik (4) , Mathieu Salanne (3)

1 LPTMC - Laboratoire de Physique Théorique de la Matière Condensée
2 PASTEUR - Processus d'Activation Sélective par Transfert d'Energie Uni-électronique ou Radiatif (UMR 8640)
3 PHENIX - PHysicochimie des Electrolytes et Nanosystèmes InterfaciauX
4 CAM - University of Cambridge [UK]

A better understanding of interfacial mechanisms is needed to improve the performances of elec-trochemical devices. Yet, simulating an electrode surface at fixed electrolyte composition remains a challenge. Here we apply a finite electric field to a single electrode held at constant potential and in contact with an aqueous ionic solution, using classical molecular dynamics. The polarization yields two electrochemical interfaces on opposite sides of the same metal slab. While the net charge on one electrode surface is the opposite of the net charge on the other, maintaining overall charge neutrality of the metal. The electrode surface charges fluctuations are compensated by the adsorption of ions from the electrolyte, forming a pair of electric double layers with aligned dipoles. This opens the way towards the efficient simulation of electrochemical interfaces using any flavor of molecular dynamics, from classical to first principles-based methods.

Domaines: Chimie

Thomas Dufils, Guillaume Jeanmairet, Benjamin Rotenberg, Michiel Sprik, Mathieu Salanne. Simulating electrochemical systems by combining the finite field method with a constant potential electrode. Physical Review Letters, 2019, 123 (19), ⟨10.1103/PhysRevLett.123.195501⟩. ⟨hal-02347013⟩