Nucleation processes of nanobubbles at a solid/water interface

Area of Science:

• Surface Science
• Nanotechnology
• Physical Chemistry

Background:

• Hydrophobic/water interfaces exhibit controversial experimental results, potentially due to uncharacterized gas accumulation.
• Understanding interfacial phenomena is crucial for various scientific and engineering applications.

Purpose of the Study:

• To investigate the initial evolution of gas-containing structures at a highly ordered pyrolytic graphite/water interface.
• To characterize the properties and behavior of interfacial nanobubbles and associated ordered domains.

Main Methods:

• Advanced atomic force microscopy (AFM) was employed to observe the dynamic formation of interfacial structures.
• Mechanical properties of fluid layers and nanobubbles were analyzed.

Main Results:

• A fluid phase initially formed as a wetting layer (~0.3 nm) and evolved into cap-shaped interfacial nanobubbles.
• Two-dimensional ordered domains nucleated and grew, confining nanobubble growth and potentially acting as hydrophilic gas hydrates or surface heterogeneities.
• Interfacial nanobubbles and fluid layers demonstrated liquid-like properties with low interfacial tension, contributing to stability and boundary slip.

Conclusions:

• Interfacial nanobubbles and ordered domains significantly alter the initially homogeneous hydrophobic interface, rendering it more heterogeneous.
• These findings have implications for understanding contact line pinning, contact angle hysteresis, and interfacial properties affecting chemical reactions and biological molecule behavior.