Colossal Pressure‐Induced Lattice Expansion of Graphite Oxide in the Presence of Water

Abstract

Expansion under compression: The unit‐cell volume of graphite oxide pressurized in water media, continuously increases reaching a sharp maximum at ca. 1.3–1.5 GPa (see picture, squares). Expansion of the lattice to a maximum of about 28–30 % is because of gradual pressure‐induced water insertion into the interlayer space of graphite oxide. The effect is reversible (triangles), resulting in a unique “breathing” of the structure upon pressure variation.

Pressure‐Induced Water Insertion in Synthetic Clays

“…We have earlier observed that graphite oxide demonstrates a counter-intuitive pressure-induced water insertion and marks the first example of a layered material showing stronger hydration (swelling) at elevated GPa pressures. [3] From a geochemical point of view, it would be rather interesting, if pressure induced water insertion similar to what was previously observed for GO, could also be found for clay minerals. If pressureinduced swelling of clays could indeed be established, it would have important implications in industry and for diverse phenomena occurring in nature.…”

“…Similarly, well defined step-like insertion of additional solvent monolayer is observed at certain pressure for Na-Hect immersed in water and shows no correlation with media solidification. It should be noted that GO compression in water results in gradual lattice expansion and in aqueous solutions it shows behavior similar to osmotic swelling of clay minerals [3,10] .…”

Modeling of hydrogen and hydroxyl group migration on graphene

“…The last result could be the key for understanding the anomalous graphene oxide expansion under water pressure [15] and may form a basis for new methods of graphene oxide total reduction [8]. …”

The structure of graphene oxide membranes in liquid water, ethanol and water–ethanol mixtures

“…Humidity-dependent studies of graphene oxide membranes 21 and paper-like materials 20 structure have been reported recently, but no structural data are available for liquid solvents. Hydration and solvation properties of precursor powder graphite oxides have been reported in our earlier studies 11,[28][29][30][31][32][33] but it is an open question to which extent these results can be applied to the GO membranes. The most striking observation is that Hummers graphite oxide powder can be intercalated by three monolayers of water (interlayer distance d(001)=12.4Å at ambient temperature), 12,35 2-3 monolayers of methanol or ethanol (d(001)=15.5Å) at ambient conditions and up to four monolayers at low temperatures (d(001)=20.6Å) 33 .…”