Rapid cryofixation/freeze fracture for the study of nanobubbles at solid–liquid interfaces

A technique borrowed from biology, rapid cryofixation/freeze fracture, has been adapted for the study of liquid–solid interfaces. This technique allows high-resolution imaging of the interfaces between water and substrates with varying degrees of hydrophobicity. The interface between gas-saturated water and hydrophobic surfaces is covered with a network of 100 nm scale features similar to those previously reported, while degassed water produces smooth interfaces. We thus confirm that the features are indeed nanobubbles which form spontaneously from dissolved gas in the liquid. The interface of gas-saturated water and a hydrophilic surface, while showing no evidence of nanobubbles, is not as smooth as the degassed interface.