Effect of external electric field on copper/silica contact electrification and adhesion: insight from first-principles and molecular mechanics investigations

Abstract

The electrostatic force induced by charge transfer during contact electrification is one of the main components of adhesion force at the solid interface. Some studies found that the magnitude of charge transfer and the consequently electrostatic force can be tuned by the external electric field. However, the detailed mechanism is still lacking in understanding. In this study, the effect of external electric field on copper/silica contact electrification and adhesion is studied via first-principles and molecular mechanics calculations and the mechanism is revealed by electrostatic potential and adhesion energy analysis. It is proved that the external electric field can affect the contact potential difference, which is the driving force of contact electrification, thus influencing the magnitude of charge transfer and electrostatic force. When the electric field direction is the same as the electron transfer direction, the contact electrification can be suppressed, leading to the decrease in the ratio of electrostatic force to van der Waals force. In particularly, the contact electrification and electrostatic force can be completely eliminated when applying a specific electric field intensity. This can provide an inspiration for quantitatively studying the source of adhesion force at solid interface.