A new mechanism of molecular diffusion across the surface of graphene has been discovered. Researchers observed that water is rapidly transported across the surface of graphene. This discovery could be used in novel filters and sensors.
Snapshot of a water nanodroplet "surfing" on a rippled graphene surface. Credit: Ming Ma et al. (2015)
A research team at University College London (UCL) conducted advanced computer simulations of water nanodroplets interacting with graphene surfaces. They observed that the droplets essentially 'surfed' over the top of the graphene, being swept along by moving ripples on the graphenes surface. As the water molecules were carried by ripples they moved at a very fast rate, which was 10 times faster than in previous observations.
The team also noticed that the fast and controllable motion of droplets of other materials could also be achieved by altering the type of molecule and the ripple size. Meaning that this behavior could be exploited in different types of applications, such as in filters and sensors.
The movement of atoms and molecules over a materials surface plays a vital role in filtration, crystal growth and molecular diffusion across catalyst surfaces.
Collaborators in this study include, Prof Gabriel Aeppli, co founder of the London Centre for Nanotechnology and now Professor of Physics at ETH Zürich and EPF Lausanne, and head of the Synchrotron and Nanotechnology Department of the Paul Scherrer Institute, Switzerland; and Dr Gabriele Tocci (formerly at the London Centre for Nanotechnology).
Atoms and molecules usually move across materials by hopping from one point on their surface to the next. However, through computer simulations we have uncovered an interesting new diffusion mechanism for motion across graphene that is inherently different from the usual random movements we see on other surfaces.
Prof. Angelos Michaelides - UCL
Our work is the culmination of an extensive and meticulously validated set of simulations which has uncovered an unexpected result that may well be at the root of the promised performance of graphene in filters and sensors.
Dr. Ming Ma - UCL
The study paper titled, “Fast diffusion of water nanodroplets on graphene,” has been published in the journal, Nature Materials.