Semiconducting nature of the oxygen-adsorbed graphene sheet

Ito, Jun; Nakamura, Jun; Natori, Akiko

doi:10.1063/1.2939270

Cited by 229 publications

(200 citation statements)

References 27 publications

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“…[41][42][43][44][45][46][47][48][49][50] The high electronegativity of oxygen atoms on carbon sheets causes the charge flow that exerts p-type semiconductivity to GO. 41,47,[51][52][53][54][55] As oxygen bonds on graphene, the valence band changes from the π-orbital of graphene to the O 2p orbital, leading to a larger bandgap for a higher oxidation level of GO. Complete oxidation converts graphene from semiconductor to insulator.…”

Section: Introductionmentioning

confidence: 99%

Graphite Oxide with Different Oxygen Contents as Photocatalysts for Hydrogen and Oxygen Evolution from Water

Yeh¹,

Teng²

2012

ECS Trans.

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Graphite oxide (GO) photocatalysts were derived from graphite oxidation. Absorption spectroscopy shows the increasing band gap of GO with the oxygen content. Electrochemical analysis along with the Mott-Schottky equation show that the conduction and valence band edge levels of GO from appropriate oxidation are suitable for both the reduction and oxidation of water. The photocatalytic activity of GO specimens with various oxygen contents was measured in methanol and AgNO 3 solutions for H 2 and O 2 evolution, respectively. The H 2 evolution was strong and stable over time whereas the O 2 evolution was negligibly small due to mutual photocatalytic reduction of the GO with upward shift of the valence band edge under illumination. The conduction band edge of GO showed negligibly change with the oxygen content. When NaIO 3 was used as a sacrificial reagent to suppress the mutual reduction mechanism under illumination, strong O 2 evolution was observed over the GO specimens. The present study demonstrates that chemical modification can easily modify the electronic properties of GO for specific photosynthetic applications. IntroductionHydrogen generation from water decomposition under light irradiation has received much attention.1-7 Photolysis of water using semiconducting photocatalyst powders is considered a prospective candidate because of the low cost in instrumentation and high interfacial contact area for reaction. [8][9][10][11][12][13][14][15][16][17] The essential requirements for an effective semiconducting photocatalyst are more negative conduction band edge and more positive valence band edge, to facilitate respectively reduction and oxidation of water. Additionally, the contact area between the catalyst and water should be large enough to execute photochemical reactions at sufficiently high gas-evolution rates. Most photocatalysts are metal-containing inorganic solids for H 2 and/or O 2 evolution from water. [18][19][20][21][22][23][24][25][26][27][28] High temperature calcination of these metal-containing photocatalysts is generally conducted for high crystallinity, 29 but it shrinks the contacting surface area with water. Molecule-like materials with accurate electronic band structure, high surface area, and stability are an alternative to the crystalline solid. [19][20][21]30,31 Graphite oxide (GO) is a polymer-like material made of carbon, oxygen, and hydrogen, having a large exposable surface area after being dispersed in water to molecular scale. 32 We demonstrated that GO can serve as a photocatalyst for H 2 evolution from water. 33 However, the conduction and valence band levels relative to those for water reduction and oxidation are yet to be explored.GO is derived from extensive oxidation of graphite and contains hydrophilic oxygen functional groups on constituting graphene sheets. [34][35][36][37][38][39][40] Therefore, GO easily disperses in aqueous solutions and exfoliates in the manner of wrinkled paper. The electronic properties of GO are related to the composition of oxygen bonding on grap...

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Section: Introductionmentioning

confidence: 99%

Graphite Oxide with Different Oxygen Contents as Photocatalysts for Hydrogen and Oxygen Evolution from Water

Yeh¹,

Teng²

2012

ECS Trans.

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“…At an O/C ratio of 50%, a finite band gap of 3.39 eV is found. 20 Attachment of a carbonyl group leads to an almost planar sp 2 electronic configuration because the formation of C ¼ O bonds induces little strain in the graphene sheet. On the contrary, attachment of an epoxy group leads to a nonplanar distorted sp 3 electronic configuration for those carbon atoms which are connected to oxygen.…”

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confidence: 99%

A first-principles investigation of the optical spectra of oxidized graphene

Singh

Kaloni

Schwingenschlögl

2013

Applied Physics Letters

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The electronic and optical properties of mono, di, tri, and tetravacancies in graphene are studied in comparison to each other, using density functional theory. In addition, oxidized monovacancies are considered for different oxygen concentrations. Pristine graphene is found to be more absorptive than any defect configuration at low energy. We demonstrate characteristic differences in the optical spectra of the various defects for energies up to 3 eV. This makes it possible to quantify by optical spectroscopy the ratios of the defect species present in a sample.

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“…However, the zero bandgap of graphene limits applications that need a high on-off ratio and rectification [9]. Several methods that have been investigated to create a bandgap, such as a bilayer stack of graphene [10,11], doping [12], and nano ribbon structure [13] are known to compromise mobility; i.e., graphene with a larger bandgap tends to have lower mobility, diluting its benefits [14].…”

Section: Introductionmentioning

confidence: 99%

Issues with the electrical characterization of graphene devices

Lee¹,

Lee²,

Jung³

et al. 2012

Carbon letters

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Graphene is an attractive material for device applications, but device characteristics are very unstable because the graphene is very sensitive to environmental factors such as charges nearby the graphene, metal contacts, defects, contaminants and other adsorbates. Since the interactions between graphene and environmental factors affect the electrical characteristics of graphene devices, the interpretation of electrical characteristics as simple as current-voltage curves is non-trivial, despite the common practice of using well known electrical characterization methods that have been used in silicon MOSFET. This paper addresses major obstacles in the electrical characterization of graphene devices and offers countermeasures to improve the accuracy of electrical characterization methods.

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Semiconducting nature of the oxygen-adsorbed graphene sheet

Cited by 229 publications

References 27 publications

Graphite Oxide with Different Oxygen Contents as Photocatalysts for Hydrogen and Oxygen Evolution from Water

Graphite Oxide with Different Oxygen Contents as Photocatalysts for Hydrogen and Oxygen Evolution from Water

A first-principles investigation of the optical spectra of oxidized graphene

Issues with the electrical characterization of graphene devices

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