On the Nature of Defects in Liquid-Phase Exfoliated Graphene

Bracamonte, M. Victoria; Lacconi, Gabriela I.; Urreta, S.E.; Torres, Luis E. F. Foa

doi:10.1021/jp501930a

Cited by 149 publications

(114 citation statements)

References 31 publications

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“…16 However, this method involves the ultrasonic treatment of graphite in solvents such as N-methyl-2-pyrrolidone (NMP), N,N-dimethylformamide (DMF), and gbutyrolactone (GBL). [17][18][19] These solvents are expensive and require special care during handling, meaning that this method is not safe, user-friendly or environmentally friendly.…”

Section: -15mentioning

confidence: 99%

Towards understanding the salt-intercalation exfoliation of graphite into graphene

Wang

Xiang

2017

RSC Adv.

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The preparation of graphene from graphite is critical for both theoretical studies and real-world applications. Herein, we present a systematic study to explore the fundamental factors that control the exfoliation of graphite into graphene in a salt-intercalation exfoliation system, using various inorganic salts as intercalators. The yields of the thin graphene sheets obtained, measured via UV-vis absorption spectrophotometry, suggest that both cations and anions significantly influence the exfoliation yields. Xray photoelectron spectroscopy and energy dispersive spectroscopy analysis showed that both anions and cations become inserted into the space between conjugated graphite layers during the intercalation process. X-ray diffraction spectra revealed that the anion can enhance the salt-intercalation exfoliation by expanding the interlayer spacing. Compared to lithium chloride, both potassium chloride and lithium sulfate can significantly enhance the exfoliation yields of graphene. Optimizing the cation and anion species can improve the yield of graphene, because co-intercalation with both anions and cations occurs during the intercalation process in the solution of inorganic salts. Our work provides a guide for rationally designing the salt-intercalation exfoliation procedure to obtain higher yields of exfoliated 2D materials.

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Section: -15mentioning

confidence: 99%

Towards understanding the salt-intercalation exfoliation of graphite into graphene

Wang

Xiang

2017

RSC Adv.

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“…Wet chemical or liquid phase exfoliation is the most promising way to mass produce high quality materials without disturbing the effects of the substrate . For the optimal quality of the outcome the effect of solvent () and the mechanical post‐procession has to be examined.…”

Section: Introductionmentioning

confidence: 99%

Transport, magnetic and vibrational properties of chemically exfoliated few-layer graphene

Márkus

Simón

Chacón-Torres

et al. 2015

Phys. Status Solidi B

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Abstractauthoren We study the vibrational, magnetic and transport properties of Few Layer Graphene (FLG) using Raman and electron spin resonance spectroscopy and microwave conductivity measurements. FLG samples were produced using wet chemical exfoliation with different post‐processing, namely ultrasound treatment, shear mixing, and magnetic stirring. Raman spectroscopy shows a low intensity D mode which attests a high sample quality. The G mode is present at 1580 cm−1 as expected for graphene. The 2D mode consists of 2 components with varying intensities among the different samples. This is assigned to the presence of single and few layer graphene in the samples. Electron Spin Resonance (ESR) spectroscopy shows a main line in all types of materials with a width of about 1 mT and a g‐factor in the range of 2.005−2.010. Paramagnetic defect centers with a uniaxial g‐factor anisotropy are identified, which shows that these are related to the local sp2 bonds of the material. All kinds of investigated FLGs have a temperature dependent resistance which is compatible with a small gap semiconductor. The difference in resistance is related to the different grain size of the samples.

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“…Prolonged irradiation is however detrimental and causes bulk defects, as shown by Raman spectroscopy in a recent study conducted in N-methyl-2-pyrrolidone (NMP), a typical solvent for graphene exfoliation. Such defects are essentially topological, while vacancies, atomic substitutions and sp 3 -like defects should be ruled out [66].…”

Section: Exfoliation Of Layered Materialsmentioning

confidence: 99%