The graphite oxide photoreduction mechanism

Plotnikov, V. G.; Смирнов, В. А.; Алфимов, М. В.; Shulga, Yury M.

doi:10.1134/s0018143911050158

Cited by 49 publications

(54 citation statements)

References 13 publications

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“…In N 2 the concentration of carboxylic compounds are always low, the only organic anion identified in traces is the acetate ion which is released in solution during the first irradiation days, presumably as a consequence of the GO photo-reduction process which releases in solution carboxylic moieties formed on the graphenic structure during the oxidation step. The release of gaseous species as a consequence of the irradiation of film or suspension of GO was previously reported [26,28,30]. In particular Shulga and co-workers [28] observed the release of CO, CO 2 , H 2 O and O 2 during the irradiation of GO films, with a main production of CO in the first steps of irradiation and a progressive and continued accumulation of CO 2 .…”

Section: -Sm)mentioning

confidence: 89%

Photochemical stability and reactivity of graphene oxide

et al. 2015

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The photoreactivity of graphene oxide (GO) suspensions was investigated with a double aim: i) to give insights into the previously reported photo-reduction process, which allows a partial elimination of the oxygen-containing groups from the 2D graphitic structure; ii) to explore the possible use of GO as photo-activator able to promote the photo-transformation/abatement of organic molecules. To reach these goals and clarify some peculiar aspects of the photochemistry of GO till now obscure or confuse, we synthesized and characterized stable GO suspensions which were then subjected to UV-Vis irradiation for prolonged times. GO underwent partial photoreduction with the release of gaseous molecules and soluble organic species (e.g. carboxylic acid).The mechanisms of photo-reduction occurring under air or N 2 are different, as assessed by the release in solution of diverse soluble molecules. In the presence of oxygen, at long irradiation time, a complete solubilization of the graphenic structures was observed. No difference in the nature and amount of released gases (principally CO 2 and CO) was observed in the oxic or anoxic conditions.The possible use of GO as photo-activator was evaluated by using phenol as probe molecule. GO revealed a double role of photo-activator and reagent in phenol degradation, as competition was assessed between GO self-transformation/reduction and phenol degradation. At prolonged irradiation time a marked reactivity of the photoformed species was observed and the complete degradation was achieved for both organic small molecules formed from GO and the phenol added as probe molecule.

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Section: -Sm)mentioning

confidence: 89%

Photochemical stability and reactivity of graphene oxide

et al. 2015

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“…Associated activation energies are 0.7 eV for OH [59], 1.9-2.1 eV for C-O-C [59,62], and 3-4 eV for C=O and COOH groups [25,58,60]. Additional, more complicated, light-induced chemistries are also possible wherein multiple functional groups (primarily hydroxyls) interact to evolve H 2 O (E a~0 .28-0.46 eV) [61].…”

Section: Go Photolysismentioning

confidence: 96%

“…A handful of studies have implicated photolysis as an alternate, light-induced means of reducing GO [25,49,58]. In a photolytic mechanism, light is absorbed by a molecular resonance associated with an oxygen-containing functionality.…”

Section: Go Photolysismentioning

confidence: 99%

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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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“…They achieved increase in conductivity by over five orders of magnitude. A group in Russia achieved photoreduction of graphene oxide films and suspensions using a mercury lamp [8] [9]. Sun's group at Jilin University in China recently reported on using a two-beam laser interference technique for patterning and reduction of graphene oxide [10] [11].…”

mentioning

confidence: 99%

Photoreduction and Thermal Properties of Graphene-Based Flexible Films

Naik¹,

Krishnaswamy²

2017

Graphene

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In the present study, we report on an efficient method for large-area photoreduction of graphene oxide flexible films. The laser-based reduction can be carried out in situ and can be tuned to attain the properties required. A systematic study has been conducted to evaluate the variation of the degree of reduction with the actual reduction temperature, which is measured using an infrared thermal camera. Local reduction temperature is varied up to 350˚C, and the degree of reduction is measured using the C/O ratio. The C/O ratio is increased from 2:1 for graphene oxide to 10:1 for reduced graphene oxide. This high degree of reduction is observed at low temperatures, and also in a short period of time. Thermal conductivity properties calculated using the temperature distribution shows the in-plane thermal conductivities of graphene oxide and reduced graphene oxide are a few orders of magnitude lower than single layer graphene. This can be attributed to oxygen-defect scattering, and also due to the heat conduction through the thickness of the sample by way of contact between adjacent flakes. This photoreduction method provides a way for roll-to-roll scalable production of graphene-based flexible films.

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The graphite oxide photoreduction mechanism

Cited by 49 publications

References 13 publications

Photochemical stability and reactivity of graphene oxide

Photochemical stability and reactivity of graphene oxide

Spectroscopy and Microscopy of Graphene Oxide and Reduced Graphene Oxide

Photoreduction and Thermal Properties of Graphene-Based Flexible Films

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