Graphene Visualizes the First Water Adlayers on Mica at Ambient Conditions

Abstract

Icy Adsorption The highly mobile nature of adsorbed liquid water on surfaces has made structural studies using atomic force microscopy challenging, especially for the first adsorbed layer. Moreover, scanning probe methods are hindered by the strong interaction between the probe tip and the water molecules. When graphene flakes were deposited on mica, Xu et al. (p. 1188 ; see the Perspective by Katsnelson ) found that they could use atomic force microscopy to image the first and second layers of introduced water. They consistently observed an islandike structure—0.34 nanometers in height, at low humidity—that corresponded to a single layer of ice. At higher humidity, thicker layers with a more liquid nature were observed.