Experimental data for water adsorption on CVD (chemical vapor deposition) graphene/SiO2 and graphene/Cu studied under ultra-high vacuum (UHV) conditions are discussed, focusing on support effects and hydrophobicity. Under UHV, it seems that graphene wettability is inversely related to wetting properties of the support. Graphene is not transparent to water wetting on the supports studied here.

Data for water adsorption on epitaxial graphene grown on Ru(0001) at ultra-high vacuum (clean conditions) are discussed. Accordingly, water adsorption was not affected by the support. The interaction is not strictly hydrophobic. We propose simple rules based on ultra-high vacuum kinetics to classify the water-graphene-support interactions.