Materials

MIT researchers develop scalable manufacturing process for graphene sheets

MIT researchers develop scalab...
MIT has created a scalable industrial process for producing large rolls of graphene filtration film
MIT has created a scalable industrial process for producing large rolls of graphene filtration film
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MIT has created a scalable industrial process for producing large rolls of graphene filtration film
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MIT has created a scalable industrial process for producing large rolls of graphene filtration film
MIT's custom-built roll-to-roll chemical vapor deposition (CVD) system for producing graphene
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MIT's custom-built roll-to-roll chemical vapor deposition (CVD) system for producing graphene

Among the almost limitless use cases for commercial-scale graphene is filtration. MIT engineers say they've now developed a scalable production process for precisely tailored graphene filtration membranes, which could see action in desalination, biological separation and other applications.

Graphene is an ultra-light, ultra-strong, super conductive, transparent carbon allotrope that resembles a chicken wire lattice at the atomic level, one that makes it impervious to even the tiniest of atoms – helium. Thus, with the right-sized holes poked in it, it can be tailored to filter out specific molecules very effectively.

The problem has always been manufacturing the damn stuff, particularly at any kind of scale, because graphene needs to be grown under very particular conditions. And that's what an MIT team believes it's cracked, using a roll-to-roll approach that's already producing up to 10 m (33 ft) of continuous graphene at a time, at a rate of 5 cm (2 in) per minute.

The process uses chemical vapour deposition, spooling a length of copper foil between two rolls and passing it slowly through two tubes. The first tube heats the foil to an ideal temperature, and in the second, a specific ratio of methane and hydrogen gas is pumped in. When this gas mixture hits the heated foil, graphene begins to form.

"Graphene starts forming in little islands, and then those islands grow together to form a continuous sheet," says John Hart, associate professor of mechanical engineering and director of the Laboratory for Manufacturing and Productivity at MIT. "By the time it's out of the oven, the graphene should be fully covering the foil in one layer, kind of like a continuous bed of pizza."

MIT's custom-built roll-to-roll chemical vapor deposition (CVD) system for producing graphene
MIT's custom-built roll-to-roll chemical vapor deposition (CVD) system for producing graphene

Once it's rolled up onto the second spool, the graphene-coated foil is cast with a polymer mesh, and the copper foil is etched away to free the graphene.

"If you don't support graphene adequately, it will just curl up on itself," says lead author Piran Kidambi, a former MIT postdoc who is now an assistant professor at Vanderbilt University. "So you etch copper out from underneath and have graphene directly supported by a porous polymer – which is basically a membrane."

The team tested the graphene membranes by passing water, salts and other molecules through them, and found the material's performance "comparable to graphene membranes made using conventional, small-batch approaches."

While the polymer casting procedure is currently done by hand, the team believes it could eventually be incorporated into the roll to roll system, making the procedure even faster and more automated.

The video below shows the system, which is detailed in a paper appearing online in the journal Applied Materials and Interfaces.

Source: MIT

Roll-to-roll graphene CVD for atomically thin membranes

5 comments
usugo
if this was the real deal, it would be a truly, yet unnoticed, revolutionary moment. But, as claims of this kind have been pretty frequent in recent years, I guess we will have to hold the celebrations till it will pass real world testing. On the other hand, an MIT research published "just" on a specialistic journal suggests that both editors and referees in the field are not really excited about the achievement. Will see
Knut
It is real, but it is also amazing, this was available 10 years ago in Europe and the Chinese use this to clean the air over Beijing. It has been developed in conjunction with emission cleaning in huge chemical plants, and the emissions that used to pollute the air is now highly valued residue, the silicon is used to produce even denser chips. But this research is not done in the US, because the EPA has not been tough enough. Their cleaning is "just to meet standards" - comply with EPA, e.g. cold sulphur removal using a Russian technology. The European chemical plants had to make filters for sub-molecular particles, and well, it was not cheap. The Chinese has acquired the technology and Mr. Trump, find your place in the queue. The Chinese got it cheap to combat emissions, place the same constraints in the US!
ljaques
Cool, a graphene pizza oven. I like it. LOL. Hopefully, this process considerably reduces the massive waste of solvents the graphene production facilities have previously used. Knut, the EPA should be on a better track now with new handlers. The old ones had companies spending massive amounts chasing down tee tiny bits of simple contaminants while allowing massive amounts of other, more toxic, substances unchecked. I'm hoping that'll stop now and they go after the large, low-hanging fruit. Cheaper and more effective filtering membranes should help all of this.
guzmanchinky
It's these little, almost unnoticed steps that lead to the lifestyle revolutions we all enjoy. love reading about these sorts of things on this site.
Eggster
Wow, add a means of safely peeling the graphene from the foil to eliminate the etching process and this really does scale dramatically.