Ultrafast Liquid Water Transport Through Graphene-Based Nanochannels Measured by Isotope Labelling

TL;DR

This study uses isotope labelling to demonstrate that liquid water can permeate graphene-based nanochannels at extremely high rates, with ions transported mainly by fast water flows, revealing fundamental insights into nanoscale mass transport.

Contribution

It provides the first detailed measurement of water and ion transport through graphene nanocapillaries without external pressure, highlighting ultrafast permeation and ion transport mechanisms.

Findings

Water diffuses through graphene channels 4-5 orders of magnitude faster than in polymeric channels.

Ions are transported mainly by water flows, with ion diffusion rates comparable to water.

Ion-wall interactions influence ion transport speed in nanocapillaries.

Abstract

Graphene-based laminates, with ultralong and tortuous nanocapillaries formed by simply stacking graphene flakes together, have great promises in filtration and separation. However, the information on liquid water trans-membrane permeation is lacking, which is the most fundamental problem and of crucial importance in solution-based mass transport. Here, based on isotope labelling, we investigate the liquid water transportation through graphene-based nanocapillaries under no external hydrostatic pressures. Liquid water can afford an unimpeded permeation through graphene-based nanochannels with a diffusion coefficient 4~5 orders of magnitude larger than through sub-micrometer-sized polymeric channels. When dissolving ions in sources, the diffusion coefficient of ions through graphene channels lies in the same order of magnitude as water, while the ion diffusion is faster than water, indicating that the ions are mainly transported by fast water flows and the delicate interactions between ions and nanocapillary walls also take effect in the accelerated ion transportation.