An electrochemical perspective on the interfacial width between two immiscible liquid phases

Molecular dynamics simulations and vibrational sumfrequency spectroscopy are historically the main techniques applied to the description of the molecular structure and dynamics of the immiscible liquidlliquid interface. A molecular sharpness is estimated for oillwater interfaces, with an interfacial width that extends from hundreds of angstrom to 1 nm. However, electrochemical studies have elucidated a deeper liquidlliquid interface on the order of several micrometers. The breaking down of single-entity electrochemistry into simpler systems and the combination of high-resolution microscopies is confirming a larger extension of the interface. What can be the role of the electrochemist in clarifying this fundamental question? We try to give a suggestion at the end of a brief historical overview of the liquidlliquid interface studies.