Combined Effects of Functional Groups, Lattice Defects, and Edges in the Infrared Spectra of Graphene Oxide

Abstract

Infrared spectroscopy in combination with density functional theory calculations has been widely used to characterize the structure of graphene oxide and its reduced forms. Yet, the synergistic effects of different functional groups, lattice defects, and edges on the vibrational spectra are not well understood. Here, we report first principles calculations of the infrared spectra of graphene oxide performed on realistic, thermally equilibrated, structural models that incorporate lattice vacancies and edges along with various oxygen-containing functional groups.Models including adsorbed water are examined as well. Our results show that lattice vacancies lead to important blue and red shifts of the OH stretching and bending bands, respectively, whereas the presence of adsorbed water leaves these shifts largely unaffected. We also find unique infrared features of edge carboxyls resulting from interactions with both nearby functional groups and the graphene lattice. Comparison of the computed vibrational properties to our experiments clarifies the origin of several observed features and provides evidence that defects and edges are essential for characterizing and interpreting the infrared spectra of graphene oxide.

Oxo‐Functionalized Graphene as a Cell Membrane Carrier of Nucleic Acid Probes Controlled by Aging

“…According to Acik et al . and Zhang et al . these bonds should give rise to characteristic stretching vibrations in the range between ≈1500 and ≈1600 cm −1 in FTIR spectra.…”

“…According to Acik et al [11] and Zhang et al [9] these bonds should give rise to characteristics tretching vibrations in the range between % 1500a nd % 1600 cm À1 in FTIR spectra.I n ac ontrol experiment,w et hermally processed( 120 8C) and chemically (HI/CF 3 CO 2 H) reduced oxo-G, which was dropcasted Scheme1.Outline of changes of the chemical structure of graphene oxide (GO) upon its aging. They include formation of sp 2 -hybridized( graphenelike)r egionsavailable for binding of afluorescents ingle-strand oligonucleotide probe F-ON (inset A) and the decreaseo fthe endoperoxidec oncentration on the oxo-G as confirmed by using af luorogenic probe F-AN-ON (inset B).…”

“…Finally, signals in FTIR spectra of two weak bands at about 1221 and 974 cm −1 were found to decrease with time and Chua and Pumera suggested that these signals correspond to epoxide vibrations . However, the unambiguous assignment is difficult, since other bands are present in this spectral (fingerprint) region, including for example, C−OH stretching or other vibrations . There is currently no consensus in the literature concerning the epoxide signals.…”

“…[7a] However,t he unambiguous assignmenti sd ifficult, since other bandsa re presenti n this spectral (fingerprint) region, including for example, CÀOH stretching or other vibrations. [9] There is currently no consensus in the literature concerning the epoxide signals. For example, in contrast to the suggestion of Chua and Pumera, [7a] De [10] and Chabal [11] assign peaks at 1230-1320 and 850 cm À1 to correspondingly stretching and bending vibrations of epoxides.…”

Basicity‐Engineered Graphite Fluoride Functionalization and Beyond: An Unusual Reaction between Ultraweak Nucleophile and Ultrastrong CF Bonds

“…For graphene functionalization community, the most commonly executed strategy is based on GO chemistry since it carries multiple active oxygenous functionalities (e.g., COOH, OH, epoxy, CO) that can be efficiently derivatized . However, during recent advances in the development of high‐performance graphene‐based electrical devices, it has been perceived that the intrinsic shortcomings of GO‐converted graphene materials, with much inferior electrically conductive properties and complicated, ambiguous structures, become the main bottlenecks and obstacles . The vigorous oxidation of graphite precursor endows the GO product substantial lattice defects even nanosized holes.…”