How to Make Large Graphene Sheets?

[sanman]

What method can be used to make large macro-sized sheets of graphene?

There have been recent articles on research showing that patchwork quilts composed of large sections of graphene have nearly the same bulk strength as pure graphene would.

http://engineering.columbia.edu/even-defects-graphene-strongest-material-world-1

So how can such a large quilt of graphene be made? What would the approach or methodology for this be?

 

[agarcia59]

You're basically asking how to find the holy grail of graphene. This has been the main question since 2004, the question that has been on the mind of many graphene researchers like myself.

Chemical vapor deposition (CVD) is currently the popular method for large area graphene growth. This is the method that the Hone group used in the article you linked.

If you haven't already, I'd suggest you search google scholar for large area graphene growth. There should be a good amount of free papers on the ArXiv if you don't have access otherwise.

 

[sanman]

As far as I know, I was the first person to ever post about graphene in this forum:

https://www.physicsforums.com/showthread.php?t=211471&highlight=graphene+silicon

But I've ben posting about it ever since I first heard of it in 2004:

https://groups.google.com/forum/?fromgroups#!topic/sci.materials/Ilq6Cqk4FcoYes, I have been Googling around, and have come across interesting Do-It-Yourself efforts like one university group which created graphene from a modified DVD-player. But the link I posted above mentioned large patchworks made of graphene sections "stitched" together. How can sections of graphene be stitched together?

It seems to me if this can be clarified and repeated, then it might be possible to create large graphene patchwork quilts of arbitrarily large size. And since my above link mentions that such quilts have overall mechanical strength comparable to pristine graphene, then this would open up the opportunity for interesting engineering experiments, such as making a large graphene balloon.

I would really really like to see how large a graphene balloon could be made before exhibiting excessive fragility and gas leakage. I've already read about a graphene nano-balloon experiment which showed its impermeability to helium. A large graphene balloon or even a graphene trampoline would be something to show the public how amazing and special graphene is.

 

[agarcia59]

Awesome! I wasn't sure what level of understanding you had, so I went with a generic reply. I'm definitely a newbie on these forums, but I'm pretty familiar with graphene.

The LightScribe method you're talking about is a pretty cool DYI method, but from my understanding, reduction of GO isn't the best way to yield quality SLG.

When Prof. Hones says "stitched together", I believe he means in terms of grain boundaries. This white arrow is pointing to a grain boundary in this image from Ahmad, M. et al. that would not be considered "well-stitched"

whereas the white arrow in this image from the same authors is pointing to a grain boundary that would be considered "well-stitched"

The grain boundaries occur due to the nature of CVD in which the precursor gas will adsorb onto the surface and nucleate, where these nucleation boundaries meet other nucleation boundaries is where grain boundaries will form.

To be honest, the graphene balloon idea sounds pretty darn cool. I am not too sure how the structural integrity of a single graphene sheet would withstand being blown up like a balloon, but it's definitely an interesting thought.

1: Muneer Ahmad et al 2012 Nanotechnology 23 285705

 

[sanman]

Hi, thanks for your kind reply!

I just wanted to quote again from this article which I already posted above:

http://engineering.columbia.edu/even-defects-graphene-strongest-material-world-1

The study verifies that commonly used methods for post-processing CVD-grown graphene weaken grain boundaries, resulting in the extremely low strength seen in previous studies. The Columbia Engineering team developed a new process that prevents any damage of graphene during transfer. “We substituted a different etchant and were able to create test samples without harming the graphene,” notes the paper’s lead author, Gwan-Hyoung Lee, a postdoctoral fellow in the Hone lab. “Our findings clearly correct the mistaken consensus that grain boundaries of graphene are weak.

I'd like to know what this different etchant is, and why it allowed the graphene to be removed from the copper substrate without harming it.

It seems to me that improvements like this could be the basis for creating larger macroscopic graphene sheets.

 

[agarcia59]

From the paper in question.

"...the copper was etched with ammonium persulfate instead of FeCl3, and polydimethylsiloxane (PDMS) was used to support the graphene during copper etching and to drystamp it onto the substrate without baking"

I'm not sure why ammonium persulfate would be a better etchant than iron chloride.

Keep in mind, this still does not allow the graphene to be absolutely pristine. Even with ammonium persulfate, they are only able to retain ~90% of graphene's strength due to defects, whereas before with iron chloride, the graphene must have been less stronger due to more defects.

In theory, one could just create a CVD furnace the size of a factory and grow a factory sized sheet of graphene on copper, using the same methods to transfer the sheet would be much trickier...

 

[sanman]

I'm curious - is there any way to theoretically calculate how big one could make an air-filled graphene balloon before it ruptured from its own size and weight?

 

[sanman]

Additionally, I wanted to ask - how can one make an elastomeric polymer skin which is impregnated with graphene? Could it ever be possible to grow graphene epitaxially by CVD onto a polymer/latex skin directly?

https://www.youtube.com/watch?v=PJQecDCS1aI

For instance, how could the above process be modified to incorporate graphene?

 

[York Fee]

Graphene balloons! The full encapsulation of helium with graphene could result in an infinite balloon or blimp holy grail indeed! This has been my obsession since reading about a helium encapsulation experiment. So very interesting! THOUGHTS?? Is this what you are getting at Sanman?