Quasi/non-equilibrium state in nanobubble growth trajectory revealed by in-situ transmission electron microscopy

Abstract

Nanobubbles have attracted significant attention in recent years for their potential applications in various fields, including engineering, environmental, biological, and medical. Furthermore, different types of nanobubbles are used for different fields due to their distinct properties. Yet, the challenge remains to understand the growth kinetics of both interfacial and bulk nanobubbles at the nanoscale to meet the requirements of different applications. Using liquid cell transmission electron microscopy, we revealed a quasi-equilibrium state in the growth trajectory of nanobubbles induced by the electron beam in the aqueous solution in real-time. Specifically, we successfully distinguished between interfacial and bulk nanobubbles by combining the analysis of growth kinetics and the Fresnel fringe method. Furthermore, the non-equilibrium growth of some nanobubbles from solution to the interface was revealed by the above method. These insights on the nanoscale growth kinetics of nanobubbles can help better engineer tailored nanobubbles with specific kinetic behaviors for different applications.