Water Transport Dynamics and Kinetic Equilibria in Nanoblisters at the Graphene-Mica Interface

Nanoscale reduced volumes with novel properties can be produced from 2D materials like graphene. Mild thermal annealing imposes vast and varied amounts of water intercalation into the graphene-mica interface, resulting in the formation of nanoblisters and impacting the local environment for applications such as reactions confined at the solid-solid interface. Atomic force microscopy imaging (AFM) and micro-Fourier transform infrared (micro-FTIR) spectroscopy characterization after 60-120 °C anneals revealed large volumes of water readily intercalate into graphene-mica nanoblisters, elucidating water transport behavior under mild reaction conditions. The inflation and deflation of graphene nanoblisters throughout the annealing process is attributed to the contraction of the graphene capping layer upon cooling from the annealing temperature, due to the independence of nanoblister aspect ratios from nanoblister volume or surface area. The intercalated water volume was estimated by the distended volumes of each nanoblister and exhibit an equilibrium trend established after 2 h of annealing. This water equilibrium occurs at a variety of temperatures, but higher temperatures favor graphene contraction and distention to accommodate larger volumes of water. Nanoblister volumes are set during the cooling process, indicating a kinetic trapping effect that can influence physical properties and reactivity for all systems confined at the graphene-mica interface.