Origin of Nanobubble - Formation of Stable Vacancy in Electrolyte Solution

Abstract

As an elementary structure of nanobubbles, vacancy, i.e., a kind of vacuum void stably exists in a liquid electrolyte solution, which is composed of an inner wall negatively charged by anion and a positively charged ionic atmosphere (R. Aogaki, Electrochemistry 76, 458 (2008)). As a result, a strong repulsing pressure induced by the attraction of the ionic atmosphere is balanced with the action of surface tension. Coalescence of vacancies guarantees the same structure as vacancy, so that the internal pressure of nano-bubbles is kept low, almost equal to the atmospheric pressure. At the same time, the variation in the chemical potential of the homogeneous formation of nano-bubbles is calculated, and it is shown that after passing a critical state corresponding to a radius of 1 nm, nanobubbles are stably created.