Spectroscopy and Microscopy of Graphene Oxide and Reduced Graphene Oxide

Abstract

Graphene oxide (GO) is an important material that provides a scalable approach for obtaining chemically derived graphene. Its optical and electrical properties are largely determined by the presence of oxygen-containing functionalities, which decorate its basal plane. This chemical derivatization results in useful properties such as the existence of a band gap as well as emission spanning both the visible and near infrared. Notably, GO's optical and electrical properties can be altered through reduction, which proceeds through the removal of these oxygen-containing functional groups. However, widely variable behavior has been observed regarding the evolution of GO's optical response during reduction. These discrepancies arise from the different reduction methods being used and, in part, from the fact that nearly all prior measurements have been ensemble studies. Consequently, detailed mechanistic studies of GO reduction are needed which can transcend the limitations of ensemble averaging.In this chapter, we show the spectroscopic evolution of GO's optical properties during photoreduction at the single-sheet level. Laser-induced reduction, in particular, offers a unique and potentially controllable method for producing reduced GO (rGO), a material with properties similar to those of graphene. However, given the complexity of GO's photoreduction mechanism, microscopic monitoring of the process is essential to understanding and ultimately exploiting this approach.

Sustainable Synthesis of High-Surface-Area Graphite Oxide via Dry Ball Milling

“…This indicates increased structural distortion (structural imperfections created by the hydroxyl, carboxyl, and epoxide groups on the carbon basal plane) and size reduction of the in-plane sp 2 domain caused by the induced mechanical stress . According to McDonald et al, the I D / I G ratio of GO is always ∼0.95, indicating a large amount of defects within the crystal lattice. Moreover, the I D / I G ratio is useful to calculate the in-plane sp 2 crystallite size ( L a ): , where λ is the wavelength of the laser source (nm).…”

“…Supporting Information (SI)) suffer from high investment or operative costs or are not sustainable due to the consumption of hazardous chemicals or the existence of impurities originating from wet chemical oxidation . Therefore, a scalable and low cost approach to obtain large quantities of graphene oxide/graphene is needed …”

Fate and Transformation of Graphene Oxide in Estuarine and Marine Waters

“…Cool white fluorescent lamps mainly emit light in the visible region (400–700 nm), with spectral peaks around 560 nm. The energy per photon at 560 nm is 2.22 eV, which exceeds the activation energies for the photolysis of C–OH (0.7 eV) and C–O–C (1.9–2.1 eV) bonds. , The activation energy for the photolysis of C=O and O–C=O groups is 3–4 eV, , which largely exceeds the energy of most of the photons emitted by the fluorescent lamp (e.g., 3.10 eV at 400 nm). Photolysis may also cause the migration of OH within the basal plane of GO (activation energy = 0.32 eV), leading to eventual OH localization at defects/edges, evolution of water, and concomitant reduction of GO .…”

A single nucleotide polymorphism electrochemical sensor based on DNA-functionalized Cd-MOFs-74 as cascade signal amplification probes

“…The Au NPs/GO nanocomposites were prepared by physical adsorption between Au NPs and GO. The as-synthesized noble metal-doped GO nanocomposites can exhibited two advantages: (1) the electrical property and carrier mobility of GO were strengthened, the GO reduced by the residual reductant in Au NPs colloidal solution during the assembly between Au NPs and GO [36].…”