Lightest-ever aerogel is only twice as heavy as hydrogen

In a Nature paper called "Solid carbon, springy and light, scientists from Zhejiang University in Hangzhou, China introduce a record-breakingly light aerogel, lighter than helium, only twice as heavy as hydrogen:

Gao Chao's team had already been building macroscopic graphene materials in one and two dimensions; to create the new aerogel, the researchers branched out into the third dimension, using a new method of freeze drying the solutions of carbon nanotubes and graphene to create malleable carbon sponges.

PhD candidate Sun Haiyan explained, "It's somewhat like large space structures such as big stadiums, with steel bars as supports and high strength film as walls to achieve both lightness and strength. Here, carbon nanotubes are supports and graphene is the wall."

The new material is amazingly absorptive, able to suck in up to 900 times its own weight in oil at a rate of 68.8 grams per second — only oil, not water, which means it has massive potential as a cleaning material when it comes to events such as oil spills.

Graphene aerogel is the new world's lightest substance [Crave/Michelle Starr]

(via Beyond the Beyond)

(Image: Graphene aerogel resting on a delicate plant, Zhejiang University))


  1. I’m confused. I assume by “lighter than” they mean “less dense than”. Shouldn’t it be floating like a helium balloon then?

    1. Sure it is lighter than helium. All you have to do is take out all the air that fills the gaps between the carbon framework and it will be buoyant. Sadly, it would collapse under the weight of the atmosphere and turn into a smudge of carbon dust.

      1. Or you could make the stuff in a helium atmosphere. Then the challenge is to keep the helium from diffusing out of its matrix.

      2. That method of measuring weight be like measuring the weight of a steel tank against its enclosed volume. That seems like a stupid idea to measure density.

      3.  Would it?  Usually 3D graphene foams have quite strong structure, and usually quite flexible and compressible.  I would have assumed that like a lot of graphene foams it would compress into a smaller shape without damage up to some point, maybe the entire way.

  2. This looks like another asbestos situation waiting to happen. If it’s small, light and able to particulate easily, it’ll end up in people’s lungs, won’t it? Or have I missed something?

  3. It is not less dense than helium. The material has a complex fine structure with lots of empty space, which fills with air. *If* you wrapped the material in an airtight seal, and pumped out the air, and the outside air pressure wasn’t enough to crush it, then the resulting object would be less dense than air.

    The same could be said of a cube outlined in pvc pipe; the only reason the aerogel is more interesting is because it’s much stronger and the empty spaces are much smaller.

  4. Is it me or does that photo look gimmicked? The sample is resting on the piece of paper behind it, and the hand is holding the grasshead next to it, and the angle of the shot makes the orientation look vertical instead of horizontal like it actually is.

  5. Sounds like if you tried to touch it, it would merge right through your finger like a nano-fine cacti?!

  6. Just make sure Detroit keeps that technology away from our SUVs. America cannot affort to lose our Gross Vehicle Weight Advantage over Europe.

  7. While the concept is endlessly fascinating to me, I have to wonder about the “can absorb up to 900x its own weight in oil” part.  If this aerogel is as light as they claim it is, then its weight is practically zero, and zero times zero is… zero.  {/snark}

    *Disclaimer: I did not read the article, I’m just pulling numbers of out the air here to illustrate the math

    ** 2nd disclaimer: I’m not dismissing this; I think it’s a brilliant idea but have to question the practicality of it.

    Now, obviously the material has a non-zero mass and therefore weight, but what is the real density and/or weight of it?  If said mass is expressed in miligrams (say, 100 mg) for a 1 meter cube, then the weight of said cube is 0.00098 newtons.  900 times 0.00098 is 0.882 newtons worth of oil.  Crude oil has a density of (roughly) 825 kg/m^3, or a weight of roughly 8085 newtons.

    So based on that, we would need roughly 9167 m^3 (about a 21 meter cube) of the aerogel to contain 1 m^3 of crude oil.  To me that only seems worthwhile if 1) the aerogel is quickly and completely reusable and 2) you can keep the oil from flowing back out until you move the gel over or into a containment vessel.

    Still, they’re really interesting structures and I hope we can figure out uses for them other than looking cool and being interesting things to talk about.

    *** Edited for dumb spelling mistake…

    1. I think it works like this: oil will soak into the material until that material is saturated, at which point the oil on the outside has no preference for being on the inside. The saturation point of the aerogel occurs at much greater density than standard cleanup materials — it would keep sucking long after the others began to blow.*

      *Megamaid ftw

    1. Even you made it in hydrogen (which is much cheaper and lighter), the structure of the aerogel would possibly prevent or at least inhibit explosions. Possibly some flame-retardant skin could be sprayed over the surface of each block of lighter-than air stuff, to keep the hydrogen in (and oxygen out).

      1. I somehow doubt that aerogel carbon will inhibit explosions. One way to make stuff explodable is to have it as finely divided dust suspended in air. Aerogel carbon seems to be pretty close to that. I’d like to see what happens when that lump of material meets a spark.

    2. I’m not sure that it still wouldn’t be heavier than a conventional Zeppelin.  They’re (usually) made of fabric and Aluminum, but that’s only the surface.  The aerogel fills the entire volume. Now it might well be more durable, I have no idea. Even helium filled zeppelins had a habit of breaking into pieces in storms.

  8. How robust is aerogel? I looks like it’d fall apart if you breathed on it, but that’d be kinda useless, so I assume it’s more robust that that. But what’s its crush strength? How does it stand up to torque? What about tension?

  9. Maybe it will help with minor oil spills, but even at a 900-1 weight ratio, it would have taken more than 85,000,000 lbs of this stuff to clean BP’s spill in the Gulf. It doesn’t really matter how cheap it is, scaling up production to those amounts, not to mention the logistics of rapid distribution to the spill scene from somewhere else in the world, make this inefficient for massive cleanups.

  10. Wait – it’s twice as heavy as hydrogen but lighter than helium?  Helium is twice as heavy as hydrogen because hydrogen is diatomic.

  11. I can’t be the only person who immediately thought of swiftfoam from the Tom Swift books.

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