Fast diffusion of water nanodroplets on graphene

TL;DR

This paper reveals a novel, rapid diffusion mechanism for water nanodroplets on graphene, where propagating ripples enable surfing-like motion, vastly exceeding traditional diffusion speeds.

Contribution

It introduces a new diffusion mechanism on layered materials like graphene, demonstrating ultrafast water nanodroplet movement and its applicability to various adsorbates.

Findings

Water nanodroplets diffuse 100-1000 times faster than in bulk water.

Propagating ripples facilitate a surfing-like diffusion mechanism.

The mechanism applies broadly to different adsorbates on layered materials.

Abstract

Diffusion across surfaces generally involves motion on a vibrating but otherwise stationary substrate. Here, using molecular dynamics, we show that a layered material such as graphene opens up a new mechanism for surface diffusion whereby adsorbates are carried by propagating ripples via a motion similar to surfing. For water nanodroplets, we demonstrate that the mechanism leads to exceedingly fast diffusion that is 2-3 orders of magnitude faster than the self-diffusion of water molecules in liquid water. We also reveal the underlying principles that regulate this new mechanism for diffusion and show how it also applies to adsorbates other than water, thus opening up the prospect of achieving fast and controllable motion of adsorbates across material surfaces more generally.