Atomic-scale mapping of hydrophobic layers on graphene and few-layer MoS<sub>2</sub> and WSe<sub>2</sub> in water.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 31197159.
- Also identified by DOI 10.1038/s41467-019-10740-w and PMC identifier 6565678.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
The structure and the role of the interfacial water in mediating the interactions of extended hydrophobic surfaces are not well understood. Two-dimensional materials provide a variety of large and atomically flat hydrophobic surfaces to facilitate our understanding of hydrophobic interactions. The angstrom resolution capabilities of three-dimensional AFM are exploited to image the interfacial water organization on graphene, few-layer MoS<sub>2</sub> and few-layer WSe<sub>2</sub>. Those interfaces are characterized by the existence of a 2 nm thick region above the solid surface where the liquid density oscillates. The distances between adjacent layers for graphene, few-layer MoS<sub>2</sub> and WSe<sub>2</sub> are ~0.50 nm. This value is larger than the one predicted and measured for water density oscillations (~0.30 nm). The experiments indicate that on extended hydrophobic surfaces water molecules are expelled from the vicinity of the surface and replaced by several molecular-size hydrophobic layers.