Electrowetting of a gold electrode by alkali bromide and iodide melts

Abstract

The potential dependence of the wetting angle on a gold electrode in sodium, potassium, and cesium bromide and iodide melts was studied to establish the laws of wetting solid surfaces with ionic melts. It is found that the forms of the contact angle vs. the potential curve for the gold electrode change from a convex to a camel-like shape with two maxima in the transition from sodium halide to potassium and cesium halide melts. This phenomenon is explained by the mutual polarization of gold and halogen ions, X−, at the place of their direct contact, which leads to the formation of ordered layers of ion associations (possibly, AuXn(n-1)–) on a positively charged surface. The hypothesis proposed agreed with the spectral observations of the electrode surface.