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

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."

Re:Other work says water diffuses through graphene

[reverseengineer]

I think this is a non-aqueous system. I don't have access to this paper, but in an earlier paper [osti.gov] 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."

Re:Other work says water diffuses through graphene

[Anonymous Coward]

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.

Re:Other work says water diffuses through graphene

[dsgrntlxmply]

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.