Evidence of Graphitic AB Stacking Order of Graphite Oxides

Abstract

Graphite oxide (GO) samples were prepared by a simplified Brodie method. Hydroxyl, epoxide, carboxyl, and some alkyl functional groups are present in the GO, as identified by solid-state 13C NMR, Fourier-transform infrared spectroscopy, and X-ray photoemission spectroscopy. Starting with pyrolytic graphite (interlayer separation 3.36 A), the average interlayer distance after 1 h of reaction, as determined by X-ray diffraction, increased to 5.62 A and then increased with further oxidation to 7.37 A after 24 h. A smaller signal in 13C CPMAS NMR compared to that in 13C NMR suggests that carboxyl and alkyl groups are at the edges of the flakes of graphite oxide. Other aspects of the chemical bonding were assessed from the NMR and XPS data and are discussed. AB stacking of the layers in the GO was inferred from an electron diffraction study. The elemental composition of GO prepared using this simplified Brodie method is further discussed.

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

“…On the other hand, GO B exhibited smaller weight losses in the 200-300 and 500-700°C temperature ranges. These results confirm the XRD ones and indicate that overall amounts of oxygen functionalities, their types, and distributions in the GO materials can be tailored by appropriate graphite oxidation parameters in agreement with earlier finding that harsher conditions and longer oxidation times result into an increased ratio of epoxides to hydroxyl groups (Boukhvalov and Katsnelson 2008;Jeong et al 2008). In the same time, the differences observed indicate a variation in the number of GO layers as shown to markedly affect the decomposition of oxygen groups, e.g., ketones and carboxyls remain above 400°C, and they are removed after a 650°C in three-layer GO materials (Acik et al 2011).…”

Surface modification of graphene and graphite by nitrogen plasma: Determination of chemical state alterations and assignments by quantitative X-ray photoelectron spectroscopy

“…The chemical states of the oxygen contamination, which entered accidentally during the plasma treatments, do not vary significantly, while its overall content changes, as shown in Table 1. The components at 398.3 ± 0.2 eV, 399.7 ± 0.2 eV and 400.9 ± 0.2 eV correspond to at least [11,31,35] and to carbon based macromolecular or polymeric substances [47,48]. The current controversy was broadly discussed in [36][37][38][39]49] and is also presented in Fig.…”

“…Before discussing a recently published set of data [5,14,40,41,47,48,[53][54][55][56][57] of surface treated nanocarbon materials, depicted in Fig. 7 (and in Table 1 in the Supplementary Information), several problems associated with the published peak-synthesis procedure and the following assignments have to be emphasized.…”

Sorption behavior of slightly reduced, three-dimensionally macroporous graphene oxides for physical loading of oils and organic solvents

“…S3). These hydroxyl groups are predominantly removed at the initial stage of thermal reduction because the binding energy of hydroxyl groups to the carbon atoms has been reported to be much lower than for other oxygen-functional groups [14][15][16][17]. The C/O ratios of the thermally reduced samples as a function of reduction time (Fig.…”