Graphene continues to dazzle us with its power and flexibility – new exciting applications are being discovered all the time, and now scientists have found a way to manipulate the miraculous material so that it can better filter impurities from water.
The two-dimensional material composed of carbon atoms has been studied as a way to purify water before, but the new method may offer the most promising approach to date. It all comes down to exploiting the so-called Van der Waals gaps: the small spaces that appear between 2D nanomaterials when layered on top of each other.
These nanochannels can be used in a variety of ways that scientists are now exploring, but the thinness of graphene poses a problem with filtration: the liquid must spend much of its time traveling in a horizontal plane rather than a vertical one, which would be much more difficult. fast.
To solve this problem, the team behind the new study used an elastic substrate to crush the graphene layer into a microscopic series of peaks and valleys. This means that the liquid can go down from the side of the top vertically, instead of walking on the open planes horizontally (all on a nanoscale, of course).
“When you start wrinkling graphene, you tilt the sheets and channels out of the plane,” said materials scientist Muchun Liu of the Massachusetts Institute of Technology (MIT).
“If you wrinkle it a lot, the channels eventually line up almost vertically.”
To complete the effect, graphene and the substrate are fixed in epoxy before cutting off the tops and bottoms of the valleys. It gives the liquid a faster path through the graphene, while allowing filtration.
Liu and her colleagues gave the new materials the name VAGME (vertically aligned graphene membranes) and further down the line, which they could find applications far beyond making drinking water safe.
“What we find ourselves in is a membrane with these short and very narrow channels that only very small molecules can pass through,” said chemical engineer Robert Hurt of Brown University.
“For example, water can pass, but organic contaminants or some metal ions would be too large to pass through. So you can filter them.”
The next step will be to put this into practice and develop a practical filtering system, but the theory is sound. The material passed one of its first tests, allowing water vapor to flow while capturing larger hexane molecules.
Ultimately, these VAGMEs can be used in industrial or domestic filtration systems, scientists say, just one of many promising ways to use graphene in a variety of scientific fields.
As for nanochannels that work between super-thin 2D materials like graphene, there’s a lot of potential here, too, according to experts. The closer scientists look at these nanomaterials, the more they discover.
“Over the last decade, a whole field has emerged to study these spaces that form between 2D nanomaterials,” says Hurt.
“You can grow things there, you can store things there, and there’s a nascent field of nanofluids where you use those channels to filter some molecules while letting others pass.”
The study was published in Nature Communications.