Dynamic Equilibrium Model for Surface Nanobubbles in Electrochemistry

Gas bubbles are ubiquitous in electrochemical processes, particularly in water electrolysis. Due to the development of gas-evolving electrocatalysis and energy conversion technology, a deep understanding of gas bubble behaviors at the electrode surface is highly desirable. In this work, by combining theoretical analysis and molecular simulations, we study the behaviors of a single nanobubble electrogenerated at a nanoelectrode. With the dynamic equilibrium model, the stability criteria for stationary surface nanobubbles are established. We show theoretically that a slight change in either the gas solubility or solute concentration results in various nanobubble dynamic states at a nanoelectrode: contact line pinning in aqueous and ethylene glycol solutions, oscillation of pinning states in dimethyl sulfoxide, and mobile nanobubbles in methanol. The above complex nanobubble behavior at the electrode/electrolyte interface is explained by the competition between gas influx into the nanobubble and outflux from the nanobubble.

Automated summary

Gas bubbles are ubiquitous in electrochemical processes, particularly in water electrolysis. A deep understanding of gas bubble behaviors at the electrode surface is highly desirable due to the development of gas-evolving electrocatalysis and energy conversion technology. By combining theoretical analysis and molecular simulations, the behaviors of a single nanobubble electrogenerated at a nanoelectrode were studied, revealing various nanobubble dynamic states based on slight changes in gas solubility or solute concentration.