Atomic and Electronic Structure of Graphene-Oxide

Abstract

We elucidate the atomic and electronic structure of graphene oxide (GO) using annular dark field imaging of single and multilayer sheets and electron energy loss spectroscopy for measuring the fine structure of C and O K-edges in a scanning transmission electron microscope. Partial density of states and electronic plasma excitations are also measured for these GO sheets showing unusual π* + σ* excitation at 19 eV. The results of this detailed analysis reveal that the GO is rough with an average surface roughness of 0.6 nm and the structure is predominantly amorphous due to distortions from sp 3 C-O bonds. Around 40% sp 3 bonding was found to be present in these sheets with measured O/C ratio of 1:5. These sp 2 to sp 3 bond modifications due to oxidation are also supported by ab initio calculations.

Influence of synthesis conditions on properties of green-reduced graphene oxide

“…10b and c depict exfoliated rGO A and PSS-rGO A as large transparent folded sheets of few hundred square nanometers resembling silk veil waves while the selected area diffraction pattern (SAED) Fig. 11 a SEM image of dry graphite oxide type A b TEM and corresponding SAED pattern of rGOA c TEM image of PSS-rGOA and d AFM image and section analysis of rGO A sheets indicated an amorphous structure for the rGO A material in agreement with the finding that harsher oxidation conditions could result in amorphous reduced graphite oxides (Mkhoyan et al 2009). …”

Coulomb blockade and hopping conduction in graphene quantum dots array

“…This has 2 been attributed to a large amount of disorder present in the RGO sheets. The structural characterization through Transmission Electron Microscopy (TEM), X-ray Photoelectron Spectroscopy (XPS), Scanning Tunneling Microscopy (STM) and Raman spectra show that RGO consists of ordered graphitic (nanocrystalline) regions surrounded by areas of oxidized carbon atoms, point defects, and topological defects [11][12][13][14][15]. The graphitic regions were estimated to be of 3-10 nm from the TEM, STM and Raman studies [11][12][13][14][15].…”

Monolithic graphene oxide sheets with controllable composition

“…Graphene in itself does not have a native oxide, and harsh chemical treatments are necessary to produce GO films 7 . GO is typically prepared by solution-based chemical means from micrometre-scale graphite flakes, and properties of GO-based devices depend on the preparation process used, which can yield a range of network morphologies of GO flakes [8][9][10][11] . Chemically derived GO is electrically insulating and must be reduced using chemical and/or thermal treatment to make it electrically active 12,13 .…”

“…A combined experimental and theoretical study shows that the Cu foil provides an effective pathway for C diffusion, trapping the O species dissolved in Cu and enabling the formation of monolithic GO sheets on its surface after an incubation time. In contrast to chemically derived GO [8][9][10][11] , the as-synthesized GO sheets are electrically active and the O/C composition in GO can be tuned during the synthesis process by controlling the O content in the Cu foil before the solid-state diffusion process. The resulting GO sheets exhibit tunable bandgap energy by varying the O/C composition, making them potentially useful for flexible and transparent semiconducting applications.…”