Liquid-Phase Exfoliation of Graphite Using the Serum from Skim Natural Rubber Latex (original) (raw)
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Exfoliation of Graphite in Various Solvents
2020
Liquid Phase Exfoliation (LPE) method has been gaining increasing interest by academic 9 and industrial researchers due to its simplicity, low-cost, and scalability. High intensity ultrasound 10 energy was exploited to transform graphite to graphene in the solvents of dimethyl sulfoxide (DMSO), 11 N,N-dimethyl formamide (DMF), and perchloric acid (PA) without any surfactants or ionic liquids. The 12 crystal structure, number of layers, particle size, and morphology of the synthesized graphene 13 samples were characterized by X-ray Diffraction (XRD), Atomic Force Microscopy (AFM), Ultraviolet 14 visible (UV–vis) spectroscopy, Dynamic Light Scattering (DLS), and Transmission Electron 15 Microscopy (TEM). XRD and AFM analyses indicated that G-DMSO and G-DMF have few layers and 16 G-PA has multilayers. The layer numbers of G-DMSO, G-DMF, and G-PA were determined as 9, 10, 17 and 21, respectively. By DLS analysis, the particle sizes of graphene samples were estimated in a 18 few micromet...
Materials Research Express, 2015
Straightforward methods to produce pristine graphene flakes in large quantities are based on the liquid-phase exfoliation processes. These one-step physical transformations of graphite into graphene offer many unique advantages. To date, a large number of liquids have been employed as exfoliation media exploiting their thermodynamic and chemical features as compared to those of graphene. Here, we pursued the goal of realizing water based mixtures to exfoliate graphite and disperse graphene without the aid of surfactants. To this aim, aqueous mixtures with suitable values of surface tension and Hansen solubility parameters (HSPs), were specifically designed and used. The very high water surface tension was decreased by the addition of solvents with lower surface tensions such as alcohols, obtaining, in this way, more favourable HSP distances. The specific role of each of these thermodynamic features was finally investigated. The results showed that the designed hydroalcoholic solutions were effective in both the graphite exfoliation and dispersion without the addition of any surfactants or other stabilizing agents. Stable graphene suspensions were obtained at concentration comparable to those produced with low-boiling solvents and water/surfactants.
Bio-Surfactant Assisted Aqueous Exfoliation of High-Quality Few-Layered Graphene
2021
Realizing the efficacy of the liquid-phase exfoliation technique to obtain a greater quantity of graphene, this study demonstrates a cost-effective technique of bio-surfactant-assisted liquid-phase exfoliation of few-layer graphene (FLG) with a low defect ratio. An ultrasonic bath without any toxic chemicals or chemical modification was employed to exfoliate the graphene at room temperature. Several state-of-the-art characterization techniques such as TEM, AFM, XRD UV-Vis, and Raman spectroscopy were used to confirm the presence of the graphene. The dispersion exhibits a typical Tyndall scattering to the red laser beam. After a 7-h sonication of the dispersion, followed by a centrifugation frequency of 500 rpm for half an hour, the graphene concentration was found to be 1.2 mg/mL. The concentration decreases monotonically with an increase in the frequency, as a higher frequency causes sedimentation of the larger flakes or removes the adsorbed surfactant molecules from the graphene s...
Advancement in liquid exfoliation of graphite through simultaneously oxidizing and ultrasonicating
J. Mater. Chem. A, 2014
Layered crystals, once exfoliated in liquids, create nanosheets with large surface area and likely generate electron band gaps. The current liquid exfoliation of graphite is performed by either oxidation, ultrasonication or the oxidation followed by ultrasonication; these methods are respectable but have limitations in general: the oxidation actually produces graphene oxide while the sonication is timeconsuming with a low yield. In this paper we report a highly effective yet simple approach for the fabrication of high-quality graphene; the approach consists of simultaneously oxidizing and ultrasonicating graphite for merely 60 min, followed by washing and filtration. Exfoliation was markedly promoted by the simultaneous treatment, where 80% of the sheets comprise single or few layers with lateral dimensions ranging 50 nm to over 100 nm; their carbon to oxygen ratio is at 8.85; the ratio of Raman D-to G-band intensity is as low as 0.211; and the sheets can be stably dispersed in acetone for at least 48 hours and they have an electrical conductivity over 600 S cm À1 . A thin graphene film made by casting exhibited a sheet resistance of $1000 U square À1 with 80% transparency at 550 nm. Fig. 6 Statistics and AFM micrographs and height profiles of graphene sheets made by oxidi-sonication for 20 min (a1-3), 40 min (b1-3) and 60 min (c1-3).
Graphene Synthesis via Exfoliation of Graphite by Ultrasonication
Graphene has newly grabbed the attention of many researchers and scholars for it's huge range of properties, mainly high surface area is the most innovative field of research. High surface area property has a great significance for its demand in almost all applications in addition to supercapacitors. Accordingly, an attempt here is accomplished to create the graphene by sonication method using ODCB solvent. Different characterization techniques are mentioned in support of the work accomplished and it is found that the interlayer distance between graphite layers increases with increasing duration of sonication process. In XRD result, it can be found that first peak at 2θ of 26.4 degree disappears and a distinguishable peak at 11.3 degree with inter graphite layer spacing in close value with 0.78 nm in association with some other diffraction peaks appear. SEM images very nicely represent homogeneous graphene film with particle size varying from 42 to 150 nm. UV-VIS absorption spectra suggests that the peak absorption in graphene decreases with high wavelengths. At 210 nm, a peak can be noticed and one more peak around 226 nm with a little bit less intensity of absorption peak can be observed in UV-VIS spectra. The details offered by SEM, XRD and UV-VIS throughputs are also mentioned. It is quoted that upon sonication the distance between graphite layers increases, thereby originating graphene. Thus it can be concluded that the graphene with enormous extraordinary properties (including Super capacitor) can be synthesized following the sonication method using organic solvents. Long hour processing via sonicator leads to formation of homogenous dispersion of graphene in case of ODCB. For thorough exfoliation of graphite, the sonication should be maintained with a very dilute system in order to reduce the importance of the graphene sheets recombination process.
Ultrasonic exfoliation of graphene in water: A key parameter study
Carbon
Liquid Phase Exfoliation (LPE) is an efficient method for graphene flake exfoliation and considered to be compatible with industrial production requirements. However, most of available LPE methods require the use of harmful and expensive solvents for chemical exfoliation prior to mechanical dispersion of the flakes, and therefore an additional step is needed to remove the contamination caused by the added chemicals, making the process complex, costly, unsafe and detrimental to the environment. By studying the effects of key ultrasonic LPE parameters, our study demonstrates the possibility to control the production and quality of few-layer graphene flakes in pure water in a relatively short period of time. The driving frequency of an ultrasonic source, a higher acoustic cavitation intensity and uniform distribution of the cavitation events in the sonicated volume are the key parameters for controlling the thickness, surface area and production yield of few-layer graphene flakes. The results are discussed in the context of mechanical exfoliation. This opens a direction for developing LPE into a cost effective, clean, environmentally friendly, and scalable manufacturing process for the next generation of twodimensional nanomaterials for industrial-scale applications.
Solid State Communications, 2009
Treatment of crystalline graphite fine powder with an aqueous solution of the harmless and versatile substance polyvinylpyrrolidone under sonication results in water-soluble, polymer-protected graphene single layers without oxidation or destruction of the sp 2 character of the carbon core. The liquid-phase extraction of graphene monolayers was evidenced by TEM and AFM techniques, while their graphitic character was checked with Raman spectroscopy. Besides PVP, the water-soluble biopolymers albumin and sodic carboxymethylcellulose were also employed successfully in the aqueous-phase exfoliation of graphite, thereby supporting the generic character of the present method using a variety of suitable polymeric extractants.
Graphene Synthesis by Ultrasound Energy Assisted Exfoliation of Graphite in Various Solvents
Liquid Phase Exfoliation (LPE) method has been gaining increasing interest by academic and industrial researchers due to its simplicity, low-cost, and scalability. High intensity ultrasound energy was exploited to transform graphite to graphene in the solvents of dimethyl sulfoxide (DMSO), N,N-dimethyl formamide (DMF), and perchloric acid (PA) without any surfactants or ionic liquids. The crystal structure, number of layers, particle size, and morphology of the synthesized graphene samples were characterized by X-ray Diffraction (XRD), Atomic Force Microscopy (AFM), Ultraviolet visible (UV–vis) spectroscopy, Dynamic Light Scattering (DLS), and Transmission Electron Microscopy (TEM). XRD and AFM analyses indicated that G-DMSO and G-DMF have few layers and G-PA has multilayers. The layer numbers of G-DMSO, G-DMF, and G-PA were determined as 9, 10, and 21, respectively. By DLS analysis, the particle sizes of graphene samples were estimated in a few micrometers. TEM analyses showed that...
Direct exfoliation of graphite and its Raman spectroscopic study
Materials Today: Proceedings, 2019
Direct exfoliating is a safer method for graphene preparation. However, it is important to synthesize a graphene with minimum structural defects since they will influence the properties of the devices. This paper focuses on two types of graphite exfoliation techniques, electrochemical and sonication, for the preparation of graphene oxides. The quality of the graphene oxides was studied using Raman Spectroscopy while the morphology was investigated by field emission scanning electron microscopy (FESEM). The results suggest that the graphene oxides synthesized using the electrochemical technique has the minimum number of layers while graphene oxides obtained from the sonication technique has the minimum defects.