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Pockets In Graphene Layers Allow Viewing of Liquids With an Electron Microscope

Posted by Unknown on from the the-emperor's-graphene-clothes dept.

slew writes "Looking at liquids with a transmission electron microscope to observe things like crystal growth has been difficult to do. This is because liquids need to be confined to a capsule to view them in a TEM (because the electrons are flying at the sample in a chamber near vaccuum pressures where liquids would evaporate or sublimate). Traditional capsules of Silicon Oxide or Silicon Nitride have been fairly opaque. A paper describes a new technique with a 'pocket' created between two graphene layers which can hold liquids for observation by a TEM and the graphene is apparently much more transparent than previous materials allowing a better view of the processes (like crystalization), taking place in the liquid. The BBC has a non-paywalled summary article."

6 of 32 comments (clear)

  1. Other work says water diffuses through graphene by ridgecritter · · Score: 4, Interesting

    TFA seems inconsistent with a recent report that graphene is so transparent to water than one can in effect use a graphene barrier to selectively out-diffuse water. (http://biology-forums.com/index.php?topic=18349.0;topicseen) gives a popularized account of the original work that indicates you can concentrate alcohol in alcohol/water solutions by simply putting a graphene film bottlecap on the bottle. Yahoo! for those of us who want to make EverClear from vodka, I guess.

    So if this story is talking about using graphene to enable TEM examination of aqueous systems, I don't see why the water doesn't diffuse rapidly out of the graphene bubble boundary, especially given the tiny volumes that would be involved in a TEM specimen.

    The graphene water diffusion paper is "Unimpeded Permeation of Water Through Helium-LeakTight Graphene-Based Membranes", paywalled at Science Mag. Really interesting.

    1. Re:Other work says water diffuses through graphene by reverseengineer · · Score: 3, Insightful

      I think this is a non-aqueous system. I don't have access to this paper, but in an earlier paper from the same group (using a silicon nitride cell) mentions that a "stock solution for synthesis was prepared by dissolving Pt(acetylacetonate)2 (10 mg/mL) in a mixture of o-dichlorobenzene and oleylamine (9:1 in volume ratio). About 100 nanoliters of the growth solution was loaded into the reservoir of a liquid cell and the solution was drawn into the cell by capillary force."

      --
      "FDA staff reviewers expressed concern about the number of patients who were left out of the study because they died."
    2. Re:Other work says water diffuses through graphene by niftydude · · Score: 4, Interesting

      TFA isn't inconsistent, not all liquids and solutions are aqueous.

      The liquid used in the experiment was a mixture of Pt(acetylacetonate)2, o-dichlorobenzene and oleylamine.

      No water was involved, though you are correct that this technique wouldn't be able to be used for aqueous sstems.

      --
      You can never know everything, and part of what you do know will always be wrong. Perhaps even the most important part.
    3. Re:Other work says water diffuses through graphene by Anonymous Coward · · Score: 3, Insightful

      A couple of things:

      1) As others have said, this system is non aqueous (Pt(acac)2 in o-dichlorobenzene and oleylamine).
      2) The graphene-as-water-filter was actually graphite oxide, which has a lot of functional groups protruding out from the basal planes into the interstices between layers. It's also still pretty unclear how the diffusion was happening at all, given that helium couldn't even wend its way through the interstitial galleries of the graphite oxide paper.

    4. Re:Other work says water diffuses through graphene by dsgrntlxmply · · Score: 3, Insightful

      What I recall from reading the graphene/water selectively permeable barrier paper (Nair et al. in Geim's research group, Science 335, 442-444 (2012)), makes the situations not comparable. The graphene in the selectively permeable barrier was not a monolayer as in this topic's paper, but rather a sort of graphene baklava: stacked monolayers with more-or-less random holes/gaps in each layer (and the graphene was oxidized). The authors offered a nanocapillary model where "a network of graphene nanocapillaries formed within GO laminates, which are filled with monolayer water under ambient conditions." Water and graphene each are extraordinary materials; put them together and things get even more extraordinary.

  2. Re:I have a graphene penis! by dsgrntlxmply · · Score: 4, Funny

    You have confused a monolayer with your nanotube.