Dependence of the shape of graphene nanobubbles on trapped substance
Authors: H. Ghorbanfekr-Kalashami, K. S. Vasu, R. R. Nair, François M. Peeters, M. Neek-Amal
Journal: Nature Communications
Publication Date: 16 June, 2017
Department of: Chemical Engineering and Analytical Science
Trapped materials fine-tune the shape of graphene nanobubbles
Stacking two-dimensional (2D) crystals on top of each other offers a unique possibility of trapping molecules at atomically smooth interfaces. These trapped substances give rise to the formation of bubbles and nanoenclosures. Van der Waals (vdW) pressure builds up (~ 1 GPa) inside these structures leading to phase transitions and unusual room temperature chemical reactions in the trapped materials. Now researchers at the University of Manchester, in collaboration with the University of Antwerp, have examined the influence of the trapped materials on the macroscopic shape and size of bubbles and the vdW pressure using state-of-the-art atomistic molecular dynamic (MD) simulations and atomic force microscopy (AFM). In simple terms, one can identify the chemical type and physical state of the trapped materials from the shape and size of bubbles and vice versa. AFM measurements show that large nanobubbles filled with hydrocarbons have a cylindrical symmetry, while those filled with water have an asymmetric shape which is in good agreement with MD simulations. The research provides insights on the physical and chemical changes in different trapped materials which can be used effectively to modulate the 2D material interfaces for the fabrication of new hybrid 2D heterostructures and chemical compounds with a wide range of applications.
- When molecules are trapped between two-dimensional (2D) crystals, the van der Waals forces that attract the adjacent 2D crystals squeeze out the trapped molecules into nanobubbles, and pressure builds up inside the bubble; we call this pressure as van der Waals pressure.
- Molecular dynamics (MD) simulation is a way of understanding the physical properties of a system, especially movement of atoms and molecules, using a computer simulation.