Simulation of Electrochemical Oxidation in Aqueous Environments under Applied Voltage Using Classical Molecular Dynamics.

Abstract

Reactive molecular dynamics (MD) simulations of metal electrodes under an applied voltage in an explicit water environment were performed and compared to predictions from both other calculations and simulations and experimental measurements and observations. MD simulations using the third-generation charge-optimized many body (COMB3) potentials and the electrode COMB (eCOMB) approach allow for the simulation of an externally applied voltage by modifying the equations of motion during the charge equilibration step (QEq) of the MD simulation. Unlike previous work, which prevented charge transfer between the water and metal electrodes, this work coupled the water and metal together through the QEq, which leads to an accumulation of a negative charge on the water and a positive charge on the metal before any voltage is applied. The extent of this charge accumulation is characterized, and strategies to mitigate it are explored. Root mean square deviation plots of the metal surfaces are created for each simulation to compare the extent of oxidation and dissolution. Good agreement is found between the oxidation behavior of the simulated metal surfaces and the experimental observations.