Pronounced, Reversible, and in Situ Modification of the Electronic Structure of Graphene Oxide via Buckling below 160 K

We have shown that the electronic structure of graphene oxide is strongly, but reversibly, affected by temperature. Below 160 K, graphene oxide is much more completely oxidized, removing any last remaining π-conjugated network. Through DFT simulations, we have shown that this is due to buckling-induced oxidation. As temperature is reduced, the lightly oxidized, graphene-like zones attempt to expand due to a negative thermal expansion coefficient (TEC), but the heavily oxidized zones, with a TEC that is near zero, prevent this from happening. This contributes to localized buckling. The deformed regions oxidize much more readily, and the 1,2-epoxide groups form a new type of functional group never before seen: a triply bonded oxygen, bonded at the 1,3,5 sites of the hexagonal carbon rings. We have called this group TB-epoxide. Stable only under buckling, the TB-epoxide groups revert back to 1,2-epoxides once the lattice relaxes to a flatter profile. We have shown that one can alter the electronic structure ...