Identification of Semiconductive Patches in Thermally Processed Monolayer Oxo-Functionalized Graphene.

The thermal decomposition of graphene oxide (GO) is a complex process at the atomic level and not fully understood. Here, a subclass of GO , oxo-functionalized graphene (oxo-G) was used to study its thermal disproportionation. We present the impact of annealing on the electronic properties of a monolayer oxo-G flake and correlated the chemical composition and topography corrugation by two-probe transport measurements, XPS, TEM , FTIR and STM. Surprisingly, we found that oxo-G, processed at 300 degrees C, bears C-C sp 3 -patches and possibly C-O-C bonds, next to graphene domains and holes. It is striking that those C-O-C/C-C sp 3 -separated sp 2 -patches with few nanometers in diameter possess semiconducting properties with a bandgap of about 0.4 eV. We propose that sp 3 -patches confine conjugated sp 2 -C what leads to the local semiconductor properties. Accordingly, graphene with sp 3 -C in double layer areas is a potential class of semiconductors and a potential target for future chemical modifications.