Structural Characterization of Graphene Oxide: Surface Functional Groups and Fractionated Oxidative Debris

Abstract

The purpose of this work is the structural analysis of graphene oxide (GO) and by means of a new structural model to answer the questions arising from the Lerf–Klinowski and the Lee structural models. Surface functional groups of GO layers and the oxidative debris (OD) stacked on them were investigated after OD was extracted. Analysis was performed successfully using Fourier transform infrared spectroscopy (FTIR), ultraviolet-visible spectroscopy (UV-Vis), X-ray photoemission spectroscopy (XPS), energy-dispersive X-ray spectroscopy (EDX), Raman spectroscopy, solid-state nuclear magnetic resonance spectroscopy (SSNMR), standardized Boehm potentiometric titration analysis, elemental analysis, X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The analysis showed that graphene oxide layers, as well as oxidative debris contain different functional groups such as phenolic –OH, ketone, lactone, carboxyl, quinone and epoxy. Based on these results, a new structural model for GO layers is proposed, which covers all spectroscopic data and explains the presence of the other oxygen functionalities besides carboxyl, phenolic –OH and epoxy groups.

Green Reduction of Graphene Oxide using Kaffir Lime Peel Extract (Citrus hystrix) and Its Application as Adsorbent for Methylene Blue

“…However, it is still unclear as to whether C=O persists even after suffering a reduction. A similar phenomenon was experienced by Aliyev et al, where the RGO produced still has C=O groups remaining even after reduction using hydrazine monohydrate 36 . Dreyer and group suggest that in the process of GO reduction, the reducing agent can breakdown the epoxy groups of GO and produce carbonyl groups 37 .…”

Graphenic Materials for Biomedical Applications

“…Characteristic absorbance at 300 nm is done by π→π* transitions of C=C bond and the n→π* transitions of C=O bond, respectively. Upon the binding of the functional groups to C=C bonds, a shift from 230 to 266 nm occurs, and the shoulder at 300 nm is reduced [27,40,45]. The proper characterization of materials used to explore possibilities outside of biomedical technologies is one of the most important steps.…”

“…Therefore, it is difficult to control the functionalization process, since different reactions may occur simultaneously [50]. Generally, the process enhances solubility and the dispersion of Analytical methods, such as scanning and transmission electron microscopy (SEM and TEM), atomic force microscopy (AFM), infrared and/or Raman spectroscopy, X-ray photoelectron spectroscopy, and inductively coupled plasma mass spectrometry (ICP/MS), are the most useful tools for characterization [4,[38][39][40]. TEM or Raman spectroscopy and AFM allow the determination of the number of layers and lateral dimensions.…”

A Review on Common Methods for Characterizing Graphene Oxide (GO)

“…But it can be changed such a way that the samples others than above under UV-visible analysis will not show these behaviors due to reduction of oxygen functionalities in graphene oxide sample, for instance, Fig. 3 (b) reported by E. Aliev et al [18].…”