Researchers gain insights into the wettability of graphene

A research team at the Center for Molecular Spectroscopy and Dynamics (CMSD) within the Institute for Basic Science (IBS) in Seoul, South Korea, and the Korea University, recently revealed the origin of the wettability of graphene. Wettability is the ability of the interfacial water to maintain contact with a solid surface, and it depends on the material’s hydrophobicity. Unlike most materials, the wettability of graphene varies depending on the type of substrate. More specifically, the wettability of the substrate is weakly affected by the presence of a single graphene layer on its surface. Such a peculiar wettability of graphene has been described by the term “wetting transparency” because the wetting properties at the graphene-water interface have little effect on the substrate-water interaction through the thin graphene.

In their new work, the team succeeded at observing the hydrogen-bond structure of water molecules at graphene-water interfaces using a technique called ‘vibrational sum-frequency generation spectroscopy (VSFG)’. VSFG is a second-order nonlinear spectroscopy that can be used to selectively analyze molecules with broken centrosymmetry. It is an ideal method for studying the behavior and structures of water molecules at the graphene interface since the water molecules in the bulk liquid are not visible due to their isotropic distribution of molecular orientations.