Density functional theory study of graphite oxide for different oxidation levels

Lahaye, R.J.W.E.; Jeong, Hyun; Park, Chae Yeon; Lee, Y. H.

doi:10.1103/physrevb.79.125435

Cited by 235 publications

(114 citation statements)

References 39 publications

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“…The measured activation volume 10.6±1.6 Å 3 compares favourably with literature values for the volumes of epoxides (13.1 Å 3 ) and for hydroxyls (14.8 Å 3 ), confirming that bonds should be removed one by one as expected 27 . Second, the activation energy of 0.73 ± 0.06 eV is comparable to previous density functional theory calculations, which found a binding energy of 0.67-0.70 eV for hydroxyls on graphene and 1.9-2.7 eV for epoxides on graphene 28,29 . Note that because we did not vary the temperature, the value of the activation energy depends on the assumed attempt frequency.…”

Section: Resultssupporting

confidence: 84%

Direct mechanochemical cleavage of functional groups from graphene

et al. 2015

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Mechanical stress can drive chemical reactions and is unique in that the reaction product can depend on both the magnitude and the direction of the applied force. Indeed, this directionality can drive chemical reactions impossible through conventional means. However, unlike heat-or pressure-driven reactions, mechanical stress is rarely applied isometrically, obscuring how mechanical inputs relate to the force applied to the bond. Here we report an atomic force microscope technique that can measure mechanically induced bond scission on graphene in real time with sensitivity to atomic-scale interactions. Quantitative measurements of the stress-driven reaction dynamics show that the reaction rate depends both on the bond being broken and on the tip material. Oxygen cleaves from graphene more readily than fluorine, which in turn cleaves more readily than hydrogen. The technique may be extended to study the mechanochemistry of any arbitrary combination of tip material, chemical group and substrate.

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Section: Resultssupporting

confidence: 84%

Direct mechanochemical cleavage of functional groups from graphene

et al. 2015

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“…The absorbed energy then dissipates through radiative or non-radiative channels or initiates a change in the chemical bond associated with the functionality. For GO, such changes include functional group migration and/or dissociation with theoretical activation energies (E a ) ranging from 0.28 to >1 eV [25,[58][59][60][61].…”

Section: Go Photolysismentioning

confidence: 99%

Spectroscopy and Microscopy of Graphene Oxide and Reduced Graphene Oxide

et al. 2015

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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.

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“…Apart from the experimental results, the theoretical characterization of the GO structure can give us a new perspective into the detail structure of GO. Lahaye et al calculated the hydroxyl and epoxy system in 2×2 GO cell using density functional theory (DFT) [46] where they found that the 1,3-ether are not likely to exist because of the joint binding energy and the single epoxy and hydroxyl prefer staying in close proximity. Boukhvalov and Katsnelson proposed a chainlike structure and found the band gap increased with the increasing oxygen coverage [47].…”

Section: Tgamentioning

confidence: 99%

“…Hydroxyl and 1, 2-ethers are two basic functional groups on the both sides of the GO sheet, so that their relative positions were firstly studied. [46,49,[67][68][69] that the nearby hydroxyl and epoxy groups tend to locate on the opposite sides of the GO sheet. This tendency can be explained by the structure distortion and tension using the MM theory.…”

Section: Determination Of Thermodynamically Stable Structuresmentioning

confidence: 99%

A theoretical study of graphene oxide chemical structure

Luo¹

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Graphene is a 2D material that has many unique and excellent physical and electrical properties.Since its discovery, people have spent much time and money on the research of graphene. A film of graphene is transparent, conductive, flexible, light in weight but very strong. Unfortunately, research in the last decade has proved that it is nearly impossible to fabricate stable, defect-free, large scale graphene sheets which have extensive application, yet without any commercial success.However, compared with the high cost of graphene film, graphene oxide (GO) is an easy-to-make material which has a similar structure. The obstacle for GO's application is its low reproducibility sincea number of oxidized side chains are difficult to remove. Even today, the GO structure model is still controversial.This study introduces a new structural model of graphene oxide and its theoretical electronic properties. A number of different models for graphene oxide have been proposed and tested using ab initio calculations. The main simulation and computation theories to establish these structure models in this study are molecular mechanics (MM) and density functional theory (DFT). In the proposed GO structure, the para-substituted epoxide groups stay in close proximity to, but on the opposite sides of the carbon plane, to the hydroxyl molecule. On the edge of GO sheet, the carboxyl prefers attachment in the armchair orientation, while the carbonyl prefers the zigzag orientation.The carbon backbone has a moderate wrinkling located around hydroxyl and epoxide molecules but still maintains a hexagonal graphene-like structure. This configuration repeats along the carbon network with subtle variations so that the chemical composition of GO is variable from 1.5 to 2.5 . And the electronic model also suggests that the band gap of GO can be theoretically tuned both by chemical reduction and controlled oxidation process.3

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Density functional theory study of graphite oxide for different oxidation levels

Cited by 235 publications

References 39 publications

Direct mechanochemical cleavage of functional groups from graphene

Direct mechanochemical cleavage of functional groups from graphene

Spectroscopy and Microscopy of Graphene Oxide and Reduced Graphene Oxide

A theoretical study of graphene oxide chemical structure

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