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1
Liu, Hong Bo, Wu Ying Zhang, Feng Lin e Hong Da Cao. "Comparison and Characterization of Two Preparation Methods of Graphene Oxide". Advanced Materials Research 989-994 (luglio 2014): 125–29. http://dx.doi.org/10.4028/www.scientific.net/amr.989-994.125.
Testo completoAbstract (sommario):
The graphene oxides were prepared form graphite by thermal expansion and ultrasonic dispersion. The structure of graphene oxides was characterized by Fourier transform infrared spectrometer (FTIR), scanning electron microscope (SEM), X-ray diffraction (XRD) and Raman spectra. The difference of structure of graphene oxides by two preparation methods was compared. The measurement of FTIR and XRD showed the graphite was completely oxidized. The graphene oxide prepared by thermal expansion would lose large number of active functional groups, such as hydroxyl, carboxyl group, et al. However, the graphene oxide prepared by ultrasonic dispersion can retain these active functional groups. These active functional groups will be benefit to chemically modify the graphene oxides and prepare the polymer/graphene nanocomposites.
2
Yıldız, Kübra, e Muhammet Uzun. "Obtaining of Reduced Graphene Oxide from Graphite by using Hummer’s and Chemical Reduction Method". Academic Perspective Procedia 2, n. 3 (22 novembre 2019): 601–5. http://dx.doi.org/10.33793/acperpro.02.03.59.
Testo completoAbstract (sommario):
In this study, graphene oxide (GO) was synthesized from graphite using modified Hummers method. According to other methods known in the literature, modified Hummers method; it is simpler and less costly in terms of process steps. In addition, it is safer and environmentally friendly than the Hummers method. Reduced Graphene Oxide (RGO) was obtained by reduction of graphene oxides (GO) synthesized by modified Hummers method. It is understood from the obtained results that GO is synthesized successfully from graphite powder by modified Hummers method and RGO is obtained successfully by reduction of graphene oxides (GO).
3
Muzyka, Roksana, Sabina Drewniak, Tadeusz Pustelny, Marcin Sajdak e Łukasz Drewniak. "Characterization of Graphite Oxide and Reduced Graphene Oxide Obtained from Different Graphite Precursors and Oxidized by Different Methods Using Raman Spectroscopy Statistical Analysis". Materials 14, n. 4 (6 febbraio 2021): 769. http://dx.doi.org/10.3390/ma14040769.
Testo completoAbstract (sommario):
In this paper, various graphite oxide (GO) and reduced graphene oxide (rGO) preparation methods are analyzed. The obtained materials differed in their properties, including (among others) their oxygen contents. The chemical and structural properties of graphite, graphite oxides, and reduced graphene oxides were previously investigated using Raman spectroscopy (RS), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD). In this paper, hierarchical clustering analysis (HCA) and analysis of variance (ANOVA) were used to trace the directions of changes of the selected parameters relative to a preparation method of such oxides. We showed that the oxidation methods affected the physicochemical properties of the final products. The aim of the research was the statistical analysis of the selected properties in order to use this information to design graphene oxide materials with properties relevant for specific applications (i.e., in gas sensors).
4
Yao, Yu Qin, Yin Jie Cen, Richard D. Sisson e Jian Yu Liang. "A Synthesize Protocol for Graphene Nanosheets". Materials Science Forum 880 (novembre 2016): 3–6. http://dx.doi.org/10.4028/www.scientific.net/msf.880.3.
Testo completoAbstract (sommario):
Chemical synthesis is cheap and easy to be tailored. Reduction of graphite oxide to form graphene nanosheets is a necessary step that determines yield, quality, chemical and surface properties of graphene nanosheets. In this report, the reduction of graphite oxides by chemical and thermal methods has been employed to convert graphite oxide synthesized by the same wet chemical method using KMnO4 and H2O2. The characterization results from the two reduction methods indicate that a combination of wet oxidation of graphite and thermal reduction method is an efficient and environmental friendly way to produce graphene.
5
Strankowski, Michał, Damian Włodarczyk, Łukasz Piszczyk e Justyna Strankowska. "Polyurethane Nanocomposites Containing Reduced Graphene Oxide, FTIR, Raman, and XRD Studies". Journal of Spectroscopy 2016 (2016): 1–6. http://dx.doi.org/10.1155/2016/7520741.
Testo completoAbstract (sommario):
Recently, graphene and other graphene-based materials have become an essential part of composite science and technology. Their unique properties are not only restricted to graphene but also shared with derivative compounds like graphene oxide, reduced graphene oxide, functionalized graphene, and so forth. One of the most structurally important materials, graphene oxide (GO), is prepared by the oxidation of graphite. Though removal of the oxide groups can create vacancies and structural defects, reduced graphene oxide (rGO) is used in composites as effective filler similar to GO. Authors developed a new polyurethane nanocomposite using a derivative of grapheme, thermally reduced graphene oxide (rGO), to modify the matrix of polyurethane elastomers, by rGO.
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Drewniak, Sabina Elżbieta, e Łukasz Drewniak. "The influence of the type of graphite on the size of reduced graphene oxide". Photonics Letters of Poland 14, n. 2 (1 luglio 2022): 34. http://dx.doi.org/10.4302/plp.v14i2.1153.
Testo completoAbstract (sommario):
Reduced graphene oxide is a very attractive material for sensor applications. It exhibits high conductivity at room temperature and high specific surface area. Since it can be produced in many ways, its properties can be influenced by the fabrication method. In this paper, we investigated the influence of graphite precursors (flake, scalar and synthetic) on the size of reduced graphene oxide. We have shown that the size of the precursor determines the size of the obtained rGO. We have noted that the larger graphite size, the larger rGO size. Full Text: PDF ReferencesR. Peng, Y. Li, T. Liu et al., "Reduced graphene oxide/SnO2@Au heterostructure for enhanced ammonia gas sensing", Chem. Phys. Lett., 737, 136829 (2019). CrossRef S. Pei and H. M. Cheng, "The reduction of graphene oxide", Carbon N. Y., 50, 9 (2012). CrossRef N. Sharma, V. Sharma, R. Vyas et al., "A new sustainable green protocol for production of reduced graphene oxide and its gas sensing properties", J. Sci. Adv. Mater. Devices, 4, 3 (2019) CrossRef R. Tarcan, O. Todor-Boer, I. Petrovai, C. Leordean, S. Astilean, I. Botiz, "Reduced graphene oxide today", J. Mater. Chem. C, 8, 4 (2020). CrossRef X. Jiao, Y. Qiu, L. Zhang, and X. Zhang, "Comparison of the characteristic properties of reduced graphene oxides synthesized from natural graphites with different graphitization degrees", RSC Adv., 7, 82 (2017). CrossRef J.A. Quezada-Renteria, C.O. Ania, L.F. Chazaro-Ruiz, J.R. Rangel-Mendez, "Influence of protons on reduction degree and defect formation in electrochemically reduced graphene oxide", Carbon N. Y., 149 (2019). CrossRef H. Gao, Y. Ma, P. Song, J. Leng, Q. Wang, "Characterization and cytocompatibility of 3D porous biomimetic scaffold derived from rabbit nucleus pulposus tissue in vitro", J. Mater. Sci. Mater. Electron., 32, 8 (2021). CrossRef A.T. Lawal, "Graphene-based nano composites and their applications. A review", Biosens. Bioelectron., 141, 111384, (2019). CrossRef E. Aliyev, V. Filiz, M.M. Khan, Y.J. Lee, C. Abetz, V. Abetz, "Structural Characterization of Graphene Oxide: Surface Functional Groups and Fractionated Oxidative Debris", Nanomaterials, 9, 8 (2019). CrossRef S. Sali, H.R. Mackey, A.A. Abdala, "Effect of Graphene Oxide Synthesis Method on Properties and Performance of Polysulfone-Graphene Oxide Mixed Matrix Membranes", Nanomaterials, 9, 5 (2019). CrossRef G. Lu, L.E. Ocola, J. Chen, "Reduced graphene oxide for room-temperature gas sensors", Nanotechnology, 20, 44 (2009). CrossRef C. Botas, P. Alvarez, C. Blanco et al., "Critical temperatures in the synthesis of graphene-like materials by thermal exfoliation–reduction of graphite oxide", Carbon N. Y., 52, 2013. CrossRef
7
Said, Muhammad, Maria Ulfa, Addy Rachmat, Desnelli e Poedji Loekitowati Hariani. "Synthesis of Reduced Graphene Oxide from Cellulose and its Applications for Methylene Blue Adsorption". Solid State Phenomena 345 (28 luglio 2023): 153–70. http://dx.doi.org/10.4028/p-n4sufo.
Testo completoAbstract (sommario):
This paper reports the synthesis and its application to the adsorption of methylene blue dye using graphene-oxide (GO) and reduced graphene-oxide (RGO). Among carbon-based nanomaterials, graphene and its derivatives have received remarkable attention due to their unique thermal, mechanical, and electronic properties and two-dimensional structure. The GO was synthesized by the modified Hummers method (chemical exfoliation) of graphite flake. This reaction produced graphite oxide (GrO) as an intermediate material. The synthesized materials, namely graphite, graphene oxide, and reduced graphene oxide, were characterized by XRD, FTIR, and Raman spectroscopy. These materials were tested to evaluate their adsorption capacity, concentration, contact time, and adsorbent weight on methylene blue, which was analyzed using a UV-vis spectrophotometer. The XRD pattern showed the formation of 2θ peaks at 24° to 26o for graphite, graphene oxide, and reduced graphene oxide, respectively. Furthermore, characterization by FTIR showed the appearance of O-H groups with peaks of 3358 cm-1 and 3342 cm-1 for graphene and reduced graphene oxides. Raman characterization indicated that reduced graphene oxide has a wavelength at the D-band peak of about 1375 cm-1 and the G-band peak reaching 1597 cm-1 with an ID/IG intensity ratio of 0.8. The adsorption test of methylene blue showed that reduced graphene oxide had the best adsorption capacity with an adsorbent, concentration, optimum time, and highest adsorption capacity value of 25 mg, 30 ppm, 45 minutes, and 15.642 mg/g. The adsorption process followed the Langmuir isotherm rule, as evidenced by the R2 value of 0.9881.
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Liu, Hong Bo, Wu Ying Zhang e Feng Lin. "Synthesis and Property of Polyurethane Acrylates Modified Graphene Oxide". Key Engineering Materials 703 (agosto 2016): 273–77. http://dx.doi.org/10.4028/www.scientific.net/kem.703.273.
Testo completoAbstract (sommario):
The graphene oxides were synthesized form graphite by ultrasonic dispersion in water, N-methylpyrrolidone (NMP), N,N-dimethyl-formamide (DMF), acetone and dimethylbenzene, and the polyurethane acrylates containing the reactive NCO (PACN) were prepared. Then the polyurethane acrylates modified graphene oxide synthesized by ultrasonic dispersion in N-methylpyrrolidone (NMP), N,N-dimethyl-formamide (DMF), acetone were prepared by NCO of PACN reacting with the hydroxyl groups of the graphene oxides. The polyurethane acrylates modified graphene oxide was characterized by Fourier transform infrared spectrometer (FTIR), scanning electron microscope (SEM) and Raman spectra. The FTIR spectra showed that the NCO of PACN reacted with the hydroxyl groups of graphene oxide synthesized by ultrasonic dispersion. The measurement of SEM and Raman spectra showed that the polyurethane acrylates modification didn't change the structure and surface morphology of graphene oxide.
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Corso, Marla, Ana Carolina de Dias Albuquerque, Lídia Pereira Amaro, Lilian Keylla Berto, Silvia Luciana Favaro, Hugo Eiji Imai, Adriano Pereira Cardoso, Natália Ueda Yamaguchi e Luciana Cristina Soto Herek Rezende. "Graphene oxide synthesis for composite material preparation". Revista Ibero-Americana de Ciências Ambientais 10, n. 1 (20 giugno 2019): 157–66. http://dx.doi.org/10.6008/cbpc2179-6858.2019.001.0013.
Testo completoAbstract (sommario):
Graphene, a material formed by carbon atoms with sp2 hybridization in a hexagonal arrangement, has differentiated characteristics in comparison to commercial materials such as high flexibility, high electrical and thermal conductivity, and strong resistance due to the organized structure of the material and can be applied in several branches of research. The best-known method for the production of graphene is the exfoliation of graphite using the methodology proposed by Hummers, in which the commercial graphite is oxidized obtaining as final product the graphene oxide that can be converted into graphene. In this study, the Hummers methodology was used in the oxidation of synthetic graphite and graphene nanoplates of 5 μm and 15 μm. The obtained materials were characterized by FTIR, RAMAN and XRD, allowing to observe the best synthesis to be used in the production of graphene oxide. Then, composites were prepared using the graphene oxides obtained as filler. In order to obtain them, different mass quantities of graphene oxides (1%, 3% and 5% in relation to the polypropylene polymer matrix) were used, demonstrating by the strain tensile stress tests that the composite materials have results more satisfactory than pure polypropylene.
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Li, Jinghao, Qiangu Yan, Xuefeng Zhang, Jilei Zhang e Zhiyong Cai. "Efficient Conversion of Lignin Waste to High Value Bio-Graphene Oxide Nanomaterials". Polymers 11, n. 4 (4 aprile 2019): 623. http://dx.doi.org/10.3390/polym11040623.
Testo completoAbstract (sommario):
Lignin graphene oxide was oxidized after Kraft lignin was graphitized by thermal catalytic conversion. The reduced lignin graphene oxide was derived from lignin graphene oxide through thermal reduction treatment. These Kraft lignin, lignin graphite, lignin graphene oxide, and reduced lignin graphene oxide were characterized by scanning electron microscopy, raman microscopy, high-resolution transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, atomic force microscopy and thermogravimetric analysis. The results showed lignin graphite converted from Kraft lignin had fewer layers with smaller lateral size than natural graphite. Moreover, lignin graphene oxide was successfully produced from lignin graphite by an oxidation reaction with an hour-long reaction time, which has remarkably shorter reaction time than that of graphene oxide made from natural graphite. Meanwhile, this lignin-derived graphene oxide had the same XRD, FTIR and Raman peaks as graphene oxide oxidized from natural graphite. The SEM, TEM, and AFM images showed that this lignin graphene oxide with 1–3 average layers has a smaller lateral size than that of graphene oxide made from natural graphite. Moreover, the lignin graphene oxide can be reduced to reduced lignin graphene oxide to fabricate graphene-based aerogel, wire, and film for some potential applications.
11
Jiříčková, Adéla, Ondřej Jankovský, Zdeněk Sofer e David Sedmidubský. "Synthesis and Applications of Graphene Oxide". Materials 15, n. 3 (25 gennaio 2022): 920. http://dx.doi.org/10.3390/ma15030920.
Testo completoAbstract (sommario):
Thanks to the unique properties of graphite oxides and graphene oxide (GO), this material has become one of the most promising materials that are widely studied. Graphene oxide is not only a precursor for the synthesis of thermally or chemically reduced graphene: researchers revealed a huge amount of unique optical, electronic, and chemical properties of graphene oxide for many different applications. In this review, we focus on the structure and characterization of GO, graphene derivatives prepared from GO and GO applications. We describe GO utilization in environmental applications, medical and biological applications, freestanding membranes, and various composite systems.
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Cao, Ning, e Yuan Zhang. "Study of Reduced Graphene Oxide Preparation by Hummers’ Method and Related Characterization". Journal of Nanomaterials 2015 (2015): 1–5. http://dx.doi.org/10.1155/2015/168125.
Testo completoAbstract (sommario):
As a novel two-dimensional carbon material, graphene has fine potential applications in the fields of electron transfer agent and supercapacitor material for its excellent electronic and optical property. However, the challenge is to synthesize graphene in a bulk quantity. In this paper, graphite oxide was prepared from natural flake graphite by Hummers’ method through liquid oxidization, and the reduced graphene oxide was obtained by chemical reduction of graphene oxide using NH3·H2O aqueous solution and hydrazine hydrate. The raw material graphite, graphite oxide, and reduced graphene oxide were characterized by X-ray diffraction (XRD), attenuated total reflectance-infrared spectroscopy (ATR-IR), and field emission scanning electron microscope (SEM). The results indicated that the distance spacing of graphite oxide was longer than that of graphite and the crystal structure of graphite was changed. The flake graphite was oxidized to graphite oxide and lots of oxygen-containing groups were found in the graphite oxide. In the morphologies of samples, fold structure was found on both the surface and the edge of reduced graphene oxide.
13
Abaszade, R. G. "Synthesis and analysis of flakes graphene oxide". Journal of Optoelectronic and Biomedical Materials 14, n. 3 (luglio 2022): 107–14. http://dx.doi.org/10.15251/jobm.2022.143.107.
Testo completoAbstract (sommario):
The presented article is devoted to the synthesis and analysis of flakes graphene oxide obtained by the Hammers method. The synthesized flakes graphene oxide was studied using SEM, EDX, X-ray diffraction, Raman spectroscopy, element analysis, temperature dependent of resistance and IR spectroscopy. As a result of calculating the results of X-ray analysis according to the Debye-Scherer’s formula, the thickness of graphite flakes was about 12,9nm and the number of layers was 38. The result of the Raman analysis show that high quality flakes grapheme oxide was obtained. Based on the result of elementary analysis of grapheme oxide mass, the C/O ratio was determined to be 1,42. The grapheme layers inside the sample were 3,31nm thick and 14,8nm long by scanning electron microscope. The temperature variation of the resistance was determined. IR spectroscopy shows the results of the absorption of electromagnetic radiation in the infrared range by atomic groups of reduced grapheme oxide and the excitation of the molecule by light quanta. When a molecule is irradiated with infrared radiation, it is shown that only quantum absorption quantities are formed according to the frequencies of the molecules.
14
P, Kavya, Soorya V. S e Binitha N. Narayanan. "Ball-Mill Assisted Green One-Pot Synthesis of ZnO/Graphene Nanocomposite for Selective Electrochemical Sensing of aquatic pollutant 4-nitrophenol". Teknomekanik 4, n. 2 (20 ottobre 2021): 64–71. http://dx.doi.org/10.24036/teknomekanik.v4i2.10872.
Testo completoAbstract (sommario):
ZnO, having good transparency, high electron mobility and lower electrical noise, is an excellent material for electrochemical studies. Due to its high surface area and electrical conductivity, graphene is well suitable for the good dispersion of metal oxides for electronic/electrochemical applications. Graphene prevents particle agglomeration, whereas the addition of metal oxide prevents layer restacking in graphene. The bulk preparation of graphene via cost-effective and green methods are preferred. The aromatic conjugated π-network along the whole surface is not attained in large scale graphite oxide assisted production due to the defects and functional groups introduced during the hazardous synthetic procedure. Here, less defective graphene is synthesised via ball milling of graphite using metal oxalate as an exfoliating agent for the first time. Calcination of metal oxalate inserted graphite leads to the enormous evolution of gases thereby sliding the graphitic layers, leading to the formation of graphene sheets decorated with ZnO spherical nanoparticles’ bunches. The layer exfoliation and metal oxide incorporation are achieved here via a one-pot synthesis strategy. The use of ZnO/graphene in the selective sensing of 4-nitrophenol is investigated using cyclic voltammetric measurements in the presence of interfering compounds such as glucose, uric acid, ascorbic acid and H2O2.
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Drewniak, Sabina Elżbieta, Roksana Muzyka e Łukasz Drewniak. "The structure of thermally reduced graphene oxide". Photonics Letters of Poland 12, n. 2 (1 luglio 2020): 52. http://dx.doi.org/10.4302/plp.v12i2.1021.
Testo completoAbstract (sommario):
The paper focused on the description of the reduced graphene oxide (rGO) structure. This material is obtained from a multistage production process. Each of these stages has a large impact on its structure (the number and type of functional groups, number of defect or the size of the flakes), and this in turn affects its properties. We would like to visualize the reduced graphene oxide, both using a diagram showing the atomic structure, as well as by imaging using scanning electron microscopy (SEM) and atomic force microscopy (AFM). In the paper, the elementary composition of selected elements and data obtained from X-ray photoelectron spectroscopy technique (XPS) will be also presented. Full Text: PDF ReferencesX. Peng, Y. Wu, N. Chen, Z. Zhu, J. Liu, and H. Wang, "Facile and highly efficient preparation of semi-transparent, patterned and large-sized reduced graphene oxide films by electrochemical reduction on indium tin oxide glass surface", Thin Solid Films 692, 137626 (2019). CrossRef L. Guo, Y.-W. Hao, P.-L. Li, J.-F. Song, R.-Z. Yang, X.-Y. Fu, S.-Y. Xie, J. Zhao and Y.-L. Zhang, "Improved NO2 Gas Sensing Properties of Graphene Oxide Reduced by Two-beam-laser Interference", Sci. Rep. 8, 1 (2018). CrossRef Y. S. Milovanov, V.A. Skryshevsky, , O.M. Slobodian, , D.O. Pustovyi, X.Tang, J.-P. Raskin, and A.N. Nazarov, "Influence of Gas Adsorption on the Impedance of Graphene Oxide", 2019 IEEE 39th Int. Conf. Electron. Nanotechnology, ELNANO 2019 - Proc. 8783946, CrossRef M. Reddeppa, B.-G. Park, , M.-D. Kim, K.R. Peta, N.D. Chinh, D. Kim, S.-G. Kim, and G. Murali, "H2, H2S gas sensing properties of rGO/GaN nanorods at room temperature: Effect of UV illumination", Sensors Actuators B. Chem. 264, (2018). CrossRef W. L. Xu, C. Ding, , M.-S. Niu, X.-Y. Yang, F. Zheng, J. Xiao, M. Zheng and X.-T. Hao, "Reduced graphene oxide assisted charge separation and serving as transport pathways in planar perovskite photodetector", Org. Electron. 81, 105663 (2020). CrossRef K. Sarkar, M. Hossain, P. Devi, K. D. M. Rao, and P. Kumar, "Self‐Powered and Broadband Photodetectors with GaN: Layered rGO Hybrid Heterojunction", Adv. Mater. Interfaces, 6, 20 (2019). CrossRef S. Pei and H. M. Cheng, "The reduction of graphene oxide", Carbon, 50, 9 (2012). CrossRef R. Muzyka, S. Drewniak, T. Pustelny, M. Chrubasik, and G. Gryglewicz, "Characterization of Graphite Oxide and Reduced Graphene Oxide Obtained from Different Graphite Precursors and Oxidized by Different Methods Using Raman Spectroscopy", Materials 11, 7 (2018). CrossRef M.-H. Tran and H. K. Jeong, "Influence of the Grain Size of Precursor Graphite on the Synthesis of Graphite Oxide", New Phys. Sae Mulli, 63, 2 (2013). CrossRef M.-H. Tran, C.-S. Yang, S. Yang, I.-J. Kim, and H. K. Jeong, "Influence of graphite size on the synthesis and reduction of graphite oxides", Curr. Appl. Phys., 14, SUPPL. 1 (2014). CrossRef N. Sharma, Y. Jain, , M. Kumari, R. Gupta, S.K. Sharma, K. Sachdev, "Synthesis and Characterization of Graphene Oxide (GO) and Reduced Graphene Oxide (rGO) for Gas Sensing Application", Macromol. Symp. 376, 1 (2017). CrossRef M. Wei, L. Qiao, , H. Zhang, S. Karakalos, K. Ma, Z. Fu, M.T. Swihart, G. Wu, "Engineering reduced graphene oxides with enhanced electrochemical properties through multiple-step reductions", Electrochim. Acta, 258 (2017). CrossRef S. Drewniak, M. Procek, R. Muzyka, T. Pustelny, "Comparison of Gas Sensing Properties of Reduced Graphene Oxide Obtained by Two Different Methods", Sensors, 20, 11 (2020). CrossRef L. Li, R.-D. Lv, S. -C. Liu, Z. D. Chen, J. Wang, Y.-G. Wang, W. Ren, "Using Reduced Graphene Oxide to Generate Q-Switched Pulses in Er-Doped Fiber Laser", Chinese Physics Letters, 35, 11 (2018) CrossRef
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Loryuenyong, Vorrada, Krit Totepvimarn, Passakorn Eimburanapravat, Wanchai Boonchompoo e Achanai Buasri. "Preparation and Characterization of Reduced Graphene Oxide Sheets via Water-Based Exfoliation and Reduction Methods". Advances in Materials Science and Engineering 2013 (2013): 1–5. http://dx.doi.org/10.1155/2013/923403.
Testo completoAbstract (sommario):
This research studied the synthesis of graphene oxide and graphene via a low-cost manufacturing method. The process started with the chemical oxidation of commercial graphite powder into graphite oxide by modified Hummer’s method, followed by the exfoliation of graphite oxide in distilled water using the ultrasound frequency from a laboratory ultrasonic bath. Finally, the oxygen functional groups on exfoliated graphite oxide or graphene oxide were eliminated by stirring in hot distilled water at 95°C, as a replacement for highly toxic and dangerously unstable hydrazine. The results assured that stirring in hot distilled water could give the product of graphene or reduced graphene oxide. The samples were characterized by FTIR, XRD, TGA, Raman spectroscopy, SEM, and TEM methods.
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Mai, Tam Thanh, Nhan Thuc Chi Ha e Huy Thuc Ha. "A new method to exfoliate Graphite oxide and application for synthesis Graphene by chemical method". Science and Technology Development Journal 17, n. 2 (30 giugno 2014): 27–34. http://dx.doi.org/10.32508/stdj.v17i2.1312.
Testo completoAbstract (sommario):
A new method to separate graphite oxide (GO) modified by polyethylene oxide (PEO) by the aid of ultrasonic radiation was developed. Modified GO (graphene oxide or single layer of graphite oxide) did not show not appear crystalline peak (d002) on the X-Ray and took the form of a single layer graphene oxide on the image AFM and TEM. The exfoliated graphene oxide was reduced (RGO) to graphene by the reducing agent system HI – Acetic acid (HI-AcOH). The sheet resistance of RGOHI-AcOH is about 120 Ω/sq in the form graphene paper. In addition, FTIR, UV-Vis and Raman spectra showed more clearly about characteristics of graphite oxide, graphene oxide and RGOHI-AcOH.
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Yu, Hui Jiang, Zheng Guang Zou, Fei Long, Chun Yan Xie e Hao Ma. "Preparation of Graphene with Ultrasound-Assisted in the Process of Oxidation". Applied Mechanics and Materials 34-35 (ottobre 2010): 1784–87. http://dx.doi.org/10.4028/www.scientific.net/amm.34-35.1784.
Testo completoAbstract (sommario):
To get single-layer of graphene, exfoliating fully intercalated graphite oxide into single- layer graphene oxide is one of the important factors. In this paper, graphite oxide prepared by the Improved Hummers Method, and ultrasound was added to the Low-temperature Reaction of this oxidation process to improve the efficiency of intercalation. Then the obtained graphene oxide was dispersed with surfactant and reduced with Hydrazine Hydrate. XRD patterns indicated that the layer distance of graphite oxide did increased at the aid of the ultrasound, and the obtained reduced products were single- and few-layer. FT-IR analysis further confirmed the preparation of graphite oxide and graphene.
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Lv, Ya Nan, Jian Fang Wang, Yin Long, Cheng An Tao, Lin Xia e Hui Zhu. "How Graphene Layers Depend on Drying Methods of Graphene Oxide". Advanced Materials Research 554-556 (luglio 2012): 597–600. http://dx.doi.org/10.4028/www.scientific.net/amr.554-556.597.
Testo completoAbstract (sommario):
Abstract: Graphite oxide is of great importance in preparing graphene, the average layer of graphene depends on that of graphene oxide in some extent. In this paper, we prepared graphite oxide via H3PO4/H2SO4mixed acid, then which were dried by vacuum drying in a freezer dryer and drying oven respectively, the graphite oxide powder and thin film were obtained correspondingly. After dispersing the above two forms of graphite oxide in water by shaking, stirring or supersonic wave, they were reduced in the same condition. According to the XRD, AFM results, vacuum freeze-drying was inclined to gain few-lay graphene.
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Minitha, Cherukutty Ramakrishnan, e Ramasamy Thangavelu Rajendrakumar. "Synthesis and Characterization of Reduced Graphene Oxide". Advanced Materials Research 678 (marzo 2013): 56–60. http://dx.doi.org/10.4028/www.scientific.net/amr.678.56.
Testo completoAbstract (sommario):
Reduced graphene oxide is an excellent candidate for various electronic devices such as high performance gas sensors. In this work Graphene oxide was prepared by oxidizing graphite to form graphite oxide. From XRD analysis the peak around 11.5o confirmed that the oxygen was intercalated into graphite. By using hydrazine hydrate, the epoxy group in graphite oxide was reduced then the solution of reduced graphite oxide (rGO) is exfoliated. Raman spectrum of rGO contains both G band (1580 cm-1), D band (1350 cm-1). The remarkable structural changes reveals that reduction of graphene oxide from the values of ID/IG ratio that increase from 0.727 (GO) to 1.414 (rGO). The exfoliated reduced graphite oxide solution is spin coated on to the SiO2/Si substrates.
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Genorio, Bostjan, e Miha Nosan. "Highly Exfoliated N-Doped Reduced Graphene Oxide Derivatives Synthesis and Application". ECS Meeting Abstracts MA2022-01, n. 7 (7 luglio 2022): 656. http://dx.doi.org/10.1149/ma2022-017656mtgabs.
Testo completoAbstract (sommario):
Carbon-based nanomaterials such as graphene, graphene oxide, carbon nanotubes, graphene nanoribbons, etc. are considered as promising materials for energy storage and conversion, electrode sensing, optical and electronic applications. High specific surface area, porosity, and chemical modifications are some of the most important factors for tailoring the (electro)chemical, physical, and mechanical properties of graphene derivatives.1 Nitrogen-doped graphene derivatives have been identified as promising materials for energy storage and conversion2 and sensing applications. One of the most common syntheses of N-doped graphene derivatives is the N-doping of graphene oxide prepared by the Hummers method. The methods for simultaneous N-doping and reduction of graphene oxide are diverse: thermal annealing, pyrolysis, solvothermal, laser ablation, microwave-assisted, and hydrazine treatment.1 However, the above methods yield N-doped graphene derivatives, which are usually poorly exfoliated and have a low specific surface area. Therefore, an efficient strategy to improve the specific surface area of N-doped graphene oxide derivatives needs to be developed.3 Herein we present a new "induction heating method" for the preparation of N-doped reduced graphene oxide derivatives (N-rGOD) with a high specific surface area. N-rGOD was prepared in a two-step process from commercially available graphites (Gs) and multi-walled carbon nanotubes (MWCNTs). In the first step, graphite oxide precursors were synthesized from Gs or MWCNTs by the improved Hummers method. In the second step, the graphite oxide precursors were subjected to rapid heat treatment by induction heating in a reductive ammonia atmosphere. Due to the rapid thermal expansion of graphite oxide, massive exfoliation occurred to obtain N-rGOD with higher specific surface area.4 These materials were tested for energy storage and conversion applications and showed excellent properties. References (1) Xu, H.; Ma, L.; Jin, Z. Nitrogen-Doped Graphene: Synthesis, Characterizations and Energy Applications. J. Energy Chem. 2018, 27 (1), 146–160. https://doi.org/10.1016/j.jechem.2017.12.006. (2) Nosan, M.; Löffler, M.; Jerman, I.; Kolar, M.; Katsounaros, I.; Genorio, B. Understanding the Oxygen Reduction Reaction Activity of Quasi-1D and 2D N-Doped Heat-Treated Graphene Oxide Catalysts with Inherent Metal Impurities. ACS Appl. Energy Mater. 2021. https://doi.org/10.1021/acsaem.1c00026. (3) Alazmi, A.; El Tall, O.; Rasul, S.; Hedhili, M. N.; Patole, S. P.; Costa, P. M. F. J. A Process to Enhance the Specific Surface Area and Capacitance of Hydrothermally Reduced Graphene Oxide. Nanoscale 2016, 8 (41), 17782–17787. https://doi.org/10.1039/c6nr04426c. (4) Qiu, Y.; Guo, F.; Hurt, R.; Külaots, I. Explosive Thermal Reduction of Graphene Oxide-Based Materials: Mechanism and Safety Implications. Carbon N. Y. 2014, 72, 215–223. https://doi.org/10.1016/j.carbon.2014.02.005.
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Chen, Dong Zhi, e Xue Mei Lin. "Preparation of Graphene by Green Reduction Method and Characterization". Advanced Materials Research 807-809 (settembre 2013): 515–20. http://dx.doi.org/10.4028/www.scientific.net/amr.807-809.515.
Testo completoAbstract (sommario):
Graphite oxide was prepared by Hummers method and got graphene oxide by ultrasonic dispersion in water, and using a cheap and environment-friendly fructose as reductant, graphene oxide could be reduced into graphene under mild condition. Meanwhile, the structure and morphology of obtained product was characterized and analyzed by testing methods such as Fourier transform Infrared spectroscopy, X-ray diffraction, Laser Raman spectroscopy, Transmission electron microscope and so on. In addition, the electrical conductivity of obtained graphene was determinated.The experimental results show that graphite oxide can be reduced by fructose under mild conditions and can get graphene with good structure and dispersibility. And the electrical conductivity of graphene prepared by the reduction of graphite oxide with fructose is 35.7 Scm-1, which has great improvement on conducting performance compared with graphite oxide. Moreover, It is non-toxic, non-polluting and friendly to the environment in preparation process of graphene, which lays the groundwork for mass production of graphene materials.
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Kamisan, Ainnur Izzati, Lili Widarti Zainuddin, Ainnur Sherene Kamisan, T. I. T. Kudin, Oskar Hasdinor Hassan, Norhana Abdul Halim e Muhd Zu Azhan Yahya. "Ultrasonic Assisted Synthesis of Reduced Graphene Oxide in Glucose Solution". Key Engineering Materials 708 (settembre 2016): 25–29. http://dx.doi.org/10.4028/www.scientific.net/kem.708.25.
Testo completoAbstract (sommario):
A new carbon material viz. graphene has been attracted an increasing research interest owing to its unique electrical and mechanical properties that is useful for the various device applications. The synthesis of graphene from graphene oxide usually involves harmful chemical reducing agents that are toxic and undesirable to human and the environment. By avoiding the use of toxic and environmentally harmful reductants, we report a green approach to effectively reduce graphene oxide to graphene in glucose solution at room temperature. Graphite oxide was synthesized from graphite powder using modified Hummers’ method. Graphite oxide then further exfoliated to graphene oxide by using ultrasonic irradiation. The mild reduction of graphene oxide is carried out by mixing graphene oxide solution with glucose. The reduction time is varied with 15, 30, 45 and 60 minutes. TEM images provide clear evidence for the formation of few layer graphene. Characterization of theresulting glucose reduced graphene oxide by FTIR indicates the partial removal of oxygen-containing functional groups from the surface of graphene oxide and formation of graphene with defects.
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N. Bonnia, N., A. Z. Zanuri, N. A. Asli, N. A. Masdar, S. Ratim, S. M. Yahaya, M. M. Mahat e R. Ramli. "Synthesis of Graphene Oxide from Waste Carbon Tyre using Modified Hummer’s Method". International Journal of Engineering & Technology 7, n. 4.14 (24 dicembre 2019): 352. http://dx.doi.org/10.14419/ijet.v7i4.14.27673.
Testo completoAbstract (sommario):
Recently, graphene was produced from graphite powder using chemical vapour deposition (CVD) or Hummer’s method. Graphene is widely used in many applications and give a lot of advantages for industry. In this study, graphene oxide was synthesized from waste carbon tyre using modified Hummer’s method. This green technology turned waste material to wealth. The morphology and structural properties of the graphene oxide were investigated using Raman spectroscopy, scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). Raman analysis was confirmed that graphene oxide was successfully synthesized from waste carbon tyre. It was confirmed the peaks shows that D band and G band was at 1361 cm-1 and 1596 cm-1 with the intensity ratio of the D band relative to the G band (ID/IG) is 0.88. The formation of few sheets of grapheme oxide that stalked together on the surface of the sample structure, bumping pieces and coarse surface was confirmed by scanning electron microscopy (SEM). The elemental composition of carbon (C) is 50.90 % and oxygen (O) is 49.10% which showed a good composition for graphene oxide. All the results were confirmed that the graphene oxide has been synthesized from waste carbon tyre using modified Hummer’s method which next will forms graphene powder through exfoliation method.
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Kane, Aichata, Ivaylo Hinkov, Ovidiu Brinza, Mongia Hosni, Aliou Hamady Barry, Salim Mourad Cherif e Samir Farhat. "One-Step Synthesis of Graphene, Copper and Zinc Oxide Graphene Hybrids via Arc Discharge: Experiments and Modeling". Coatings 10, n. 4 (25 marzo 2020): 308. http://dx.doi.org/10.3390/coatings10040308.
Testo completoAbstract (sommario):
In this paper, we report on a modified arc process to synthetize graphene, copper and zinc oxide graphene hybrids. The anode was made of pure graphite or graphite mixed with metals or metal oxides. After applying a controlled direct current, plasma is created in the interelectrode region and the anode is consumed by eroding. Continuous and abundant flux of small carbon, zinc or copper species, issued from the anode at a relatively high temperature, flows through the plasma and condenses in the vicinity of a water-cooled cathode leading to few-layered graphene sheets and highly ordered carbon structures. When the graphite rod is filled with copper or zinc oxide nanoparticles, few layers of curved graphene films were anchored with spherical Cu and ZnO nanoparticles leading to a one-step process synthesis of graphene hybrids, which combine the synergetic properties of graphene along with nanostructured metals or semiconducting materials. The as-prepared samples were characterized by Raman spectroscopy, X-ray diffraction (XRD), spatially resolved electron energy loss spectroscopy (EELS), energy filtered elemental mapping and transmission electron microscopy (TEM). In addition to the experimental study, numerical simulations were performed to determine the velocity, temperature and chemical species distributions in the arc plasma under specific graphene synthesis conditions, thereby providing valuable insight into growth mechanisms.
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Lei, Yun, Jun Xu, Rong Li e Fei Fei Chen. "Acidification Assisted Preparation of Graphite Oxide and Graphene". Advanced Materials Research 988 (luglio 2014): 36–39. http://dx.doi.org/10.4028/www.scientific.net/amr.988.36.
Testo completoAbstract (sommario):
Graphite oxide was prepared by acidification assisted Hummers method, which contains acidification, medium temperature and high-temperature three stages. Traditional Hummers low-temperature process was replaced by acidification process. The dosages of acid, graphite and potassium permanganate were investigated, and the produced graphite oxide was treated by ultrasonic oscillation and reduced to graphene by refluxing the reaction mixture at 100°C under open-air conditions. The structure of natural graphite, graphite oxide and graphene were characterized by X-ray diffractometry and infrared spectrum, the morphology of graphene was observed on a scanning electron microscope and the electrochemical properties of graphene were analyzed by the three-electrode cyclic voltammetry test system.
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Kamisan, Ainnur Izzati, Ainnur Sherene Kamisan, Ruslinda Md Ali, Tunku Ishak Tunku Kudin, Oskar Hasdinor Hassan, Norhana Abdul Halim e Mohamad Faizul Yahya. "Synthesis of Graphene via Green Reduction of Graphene Oxide with Simple Sugars". Advanced Materials Research 1107 (giugno 2015): 542–46. http://dx.doi.org/10.4028/www.scientific.net/amr.1107.542.
Testo completoAbstract (sommario):
A new carbon material called graphene has been attracting an increasing research interest owing to its unique electrical and mechanical properties that is useful for the various device applications. The synthesis of graphene from graphene oxide usually involves harmful chemical reducing agents that are toxic and undesirable to human and the environment. By avoiding the use of toxic and environmentally harmful reductants, we report a green approach for the reduction of graphene oxide by using reducing sugars to synthesis graphene. Graphite oxide was synthesized from graphite powder using modified Hummers method. Graphite oxide then further exfoliated to graphene oxide by using ultrasonic irradiation. Graphene then was obtained by the mild reduction of graphene oxide with reducing sugars (glucose, lactose and maltose). The structural study of the as-prepared graphene is characterized by Raman spectroscopy and fourier infra red spectroscopy. Raman and FTIR spectra indicates the partial removal of oxygen functional groups from the surface of GO. Characterizations indicate that graphene oxide is successfully reduced to graphene by sugar.
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Li, Pei Pei, e Bao Xiang Deng. "Research on Carbon Materials with Synthesis and Characterization of Graphene-Based". Advanced Materials Research 1003 (luglio 2014): 100–104. http://dx.doi.org/10.4028/www.scientific.net/amr.1003.100.
Testo completoAbstract (sommario):
Carbon materials has been a popular application materials, especially in graphene. Graphene, the mother of all graphitic materials, has emerged to become an exciting two-dimensional material with wondrous properties. Atomic and electronic structures of graphene have been investigated by employing a variety of micro-scopic, spectroscopic, and other techniques. The results show it has better thermal stability, and larger surface area than graphite, graphite oxide. Keywords: graphite; oxidation-reduction method; graphite oxide; graphene
29
Andrijanto, Eko, Gatot Subiyanto, Nina Marlina, Hanifa Citra e Cahya Lintang. "Preparation of Graphene Oxide Sand Composites as Super Adsorbent for Water Purification Application". MATEC Web of Conferences 156 (2018): 05019. http://dx.doi.org/10.1051/matecconf/201815605019.
Testo completoAbstract (sommario):
This paper describes a method to synthesize a graphene oxide sand composites (GSC) as filter media (absorbent) for water purification. Graphene oxides is synthesized from graphite using modification of Hummer's method. The graphene oxide sand composites is prepared through solution method at 100 °C. The graphene oxide is analyzed using XRD, FTIR to confirm its formation. The FTIR spectrum and XRD diffraction pattern confirmed that the graphene oxide synthesized by this method is able to convert graphite into graphene oxide. Performance tests were conducted using a column to purify contaminated water which was mimicked using dyes such as rhodamine B, methylene blue and methyl orange.The initial concentration for all dyes were set for 5, 10, 25, 50 and 100 ppm. The color removal for methylene blue was 100% at all concentrations. However, for the rhodamine B and methyl orange, the color removal achieved 100% for the first three concentration 5, 10 and 25 ppm. The higher concentration of 50 and 100 ppm, the removal were slightly reduced. For the 50 ppm, the color removal of rhodamine B was 98% and for methyl orange 87% respectively. At 100 ppm, the color removal for rhodamine B drops to 92% and for the methyl orange was only 77% respectively. The GSC was very effective to remove methylene blue dyes at any concentration followed by rhodamine B and methyl orange. This GSC composite material is potential to be applied for water purification.
30
Iakunkov, Artem, e Alexandr V. Talyzin. "Swelling properties of graphite oxides and graphene oxide multilayered materials". Nanoscale 12, n. 41 (2020): 21060–93. http://dx.doi.org/10.1039/d0nr04931j.
Testo completoAbstract (sommario):
Swelling defines graphite oxides and multilayered graphene oxides. It is a key property of GO in applications which involve sorption from vapors, immersion into liquid water or polar solvents and solution based chemical reactions.
31
Bastiurea, Marian, Dumitru Dima e Gabriel Andrei. "Effect of Graphene Oxide and Graphite on Dry Sliding Wear Behavior of Polyester Composites". Materiale Plastice 55, n. 1 (30 marzo 2018): 102–10. http://dx.doi.org/10.37358/mp.18.1.4973.
Testo completoAbstract (sommario):
Graphene oxide and graphite filled polyester composites were prepared by using conventional melt-mixing methods in order to improve tribological performance of polyester. It was investigated friction stability, microhardness, friction coefficient, and specific wear rate of the composites in details. It was found that the presence of graphite and graphene oxide influenced friction coefficient and wear rate of the composites. Graphene oxide decreased wear rate with increasing of test speed and graphite decreased wear rate for composite for all speeds. Tribological performance of the polyester/graphene composites is mainly attributed to bigger thermal conductivity for graphene, which can easily dissipate the heat which appears during the friction process at bigger forces. The positive influence of graphite on coefficient of friction (COF) of the composites is the result of the clivage of graphite layers during the loadings due to van der Waals weak bonds between the graphite layers.
32
Evseev, Zakhar Ivanovich, Fedora Dmitrievna Vasileva, Svetlana Afanasyevna Smagulova e Petr Stanislavovich Dmitriev. "Highly Washable and Conductive Cotton E-textiles Based on Electrochemically Exfoliated Graphene". Materials 16, n. 3 (19 gennaio 2023): 958. http://dx.doi.org/10.3390/ma16030958.
Testo completoAbstract (sommario):
In this study, cotton e-textiles were obtained using two types of graphene oxide. The first type of graphene oxide was synthesized using the Hummers’ method. The second type was obtained by the electrochemical exfoliation of graphite in an ammonium salt solution. It was shown that e-textiles based on electrochemically exfoliated graphene have a higher electrical conductivity (2 kΩ/sq) than e-textiles based on graphene oxide obtained by the Hummers’ method (585 kΩ/sq). In addition, textiles based on electrochemically exfoliated graphene exhibit better washing and mechanical stress stability. The electrical resistance of the e-textiles increased only 1.86 times after 10 cycles of washing, compared with 48 times for the Hummers’ method graphene oxide textiles. The X-ray photoelectron spectra of the two types of graphene oxides showed similarity in their functional compositions after reduction. Studies of individual graphene flakes by atomic force microscopy showed that graphene oxide of the second type had a smaller lateral size. Raman spectroscopy showed a higher degree of sp2 structure regeneration after reduction for the second type of graphene. These properties and the tendency to form agglomerated particles determine the mechanochemical stability and high electrical conductivity of e-textiles based on electrochemically exfoliated graphene.
33
Miao, Zheng, Rong Xia Zhu e Li Xia Zhang. "Research on Preparation and Morphology of GO and GO/Fe3O4 Composite". Materials Science Forum 1026 (aprile 2021): 117–21. http://dx.doi.org/10.4028/www.scientific.net/msf.1026.117.
Testo completoAbstract (sommario):
Graphite oxide was prepared from 325 mesh graphite (G) in this paper with methods of Hummers method,sulphuric/phosphoric acid method and reaction kettle method, the Graphene Oxides (GO) were obtained with ultrasonic treatment. Then Fe3O4 particles of two different proportions and hydrazine hydrate were introduced into one of the GO to obtain GO/Fe3O4 composites. X-ray diffraction (XRD) was used to characterize the G,the obtained graphite oxide and GO/Fe3O4 respectively. Scanning electron microscopy (SEM) was used to characterize the obtained GO and GO/ Fe3O4 composites.The results show that the GO obtained by the way of sulphuric/phosphoric acid has the best pattern and the nanoparticle scale decreased as the proportion of GO in GO/Fe3O4 increased.
34
Liu, Li Lai, Mao Zhong An, Shan Chao Xing, Xiao Jun Shen, Chen Yang e Xin Long Xu. "Preparation of Graphene Oxide Based on Expanded Graphite". Advanced Materials Research 881-883 (gennaio 2014): 1083–88. http://dx.doi.org/10.4028/www.scientific.net/amr.881-883.1083.
Testo completoAbstract (sommario):
Graphene oxide with high degree of oxidation and peelable has been prepared by two-step oxidation method used large flake graphite. The expanded graphite was prepared firstly and then prepared graphene oxide via further oxidation. The influence of oxidation time, oxidant dosage and high temperature reaction on the structure and degree of oxidation were studied. The morphology and structure of graphene oxide were characterized by X-ray diffraction, fourier transform infrared spectra, scanning electron microscope and transmission electron microscope. It was found that high degree of oxidation and large specific surface area graphene oxide was prepared at the ratio of sulfuric acid and expanded graphite was 75 mL : 1 g, the ratio of potassium permanganate and expanded graphite was 4 g : 1 g and the oxidation time at 35 °C was 24 h. This technology is simple without high-temperature reaction process, and solved the problem of low oxidation efficiency when used the large flake graphite as raw materials.
35
Guo, Qiaoqin, Zhong Yang, Ding Guo, Dong Tao, Yongchun Guo, Jianping Li e Yaping Bai. "Research on the Oxidation Mechanism of Vermicular Graphite Cast Iron". Materials 12, n. 19 (25 settembre 2019): 3130. http://dx.doi.org/10.3390/ma12193130.
Testo completoAbstract (sommario):
The oxidation mechanism of vermicular graphite cast iron was studied. The oxidation reaction starts from graphites and diffused slowly. Graphites in vermicular graphite are interconnected, coral-like clusters, providing the main oxidation core and channel. The worm-like graphites on the surface are mostly oxidized and form oxide affected zones. The oxide films are composed of a loose oxide layer with the phases of Fe3O4, Fe2O3, and FeO, and a dense passivation layer with FeO and Fe2SiO4. After oxidation, pearlites in the vermicular graphite cast iron are decomposed into ferrite and cementite at high temperatures.
36
Thema, F. T., M. J. Moloto, E. D. Dikio, N. N. Nyangiwe, L. Kotsedi, M. Maaza e M. Khenfouch. "Synthesis and Characterization of Graphene Thin Films by Chemical Reduction of Exfoliated and Intercalated Graphite Oxide". Journal of Chemistry 2013 (2013): 1–6. http://dx.doi.org/10.1155/2013/150536.
Testo completoAbstract (sommario):
Commercial flakes of graphite were prepared into functionalized graphene oxide (GO) by chemical treatment. After the exfoliation and intercalation of graphene into functionalized graphene oxide that formed stable colloidal dispersion in polar aprotic solvent, the reduction process was undertaken by continuous stirring with hydrazine hydrate. The reduced material was characterized by X-ray diffraction (XRD), attenuated total reflectance (ATR) FT-IR, ultraviolet visible (UV-vis), atomic force microscopy (AFM) and Raman spectroscopy which confirm the oxidation of graphite and reduction of graphene oxide into graphene sheet.
37
Chong, S. W., Chin Wei Lai, Sharifah Bee Abd Hamid, F. W. Low e Wei Wen Liu. "Simple Preparation of Exfoliated Graphene Oxide Sheets via Simplified Hummer’s Method". Advanced Materials Research 1109 (giugno 2015): 390–94. http://dx.doi.org/10.4028/www.scientific.net/amr.1109.390.
Testo completoAbstract (sommario):
Today, research on graphene and other two-dimensional sp2-hybridized carbon nanomaterials has tremendously impacted the areas of modern chemistry, physics, and materials science and engineering. The significant attraction of these materials can be attributed to the outstanding electrical, optical, electrochemical, and mechanical properties of graphene-like materials, especially in comparison to other carbon materials. In this manner, graphene oxide as a substrate for graphene-like materials reduction process is getting more and more interesting. Although early routes to these materials were challenging, significant advances in synthetic and processing methods have enabled access to high-quality exfoliated graphene oxide sheets in appreciable quantities. Herein, we introduced a simple and efficient method for the high-conversion preparation of graphene oxide using a simplified hummer’s method from large graphite flakes (an average flake size of 100 μm). One-pot chemical oxidation of graphite was carried out at room temperature for the preparation purpose. It was found that different degree of oxidation of graphite flakes could be realized by stirring graphite in a mixture of sulphuric acid and potassium permanganate under different oxidation durations, resulting in exfoliated graphene oxide sheets with large lateral dimension and area. The simplified Hummer’s method provides a facile approach for the preparation of large-area exfoliated graphene oxide sheets.
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Nasir, Salisu, Mohd Zobir Hussein, Zulkarnain Zainal e Nor Azah Yusof. "Development of New Carbon-Based Electrode Material from Oil Palm Waste-Derived Reduced Graphene Oxide and Its Capacitive Performance Evaluation". Journal of Nanomaterials 2019 (29 novembre 2019): 1–13. http://dx.doi.org/10.1155/2019/1970365.
Testo completoAbstract (sommario):
This paper is an expansion of our previous work on the synthesis of graphene oxides and reduced graphene oxides from different kinds of oil palm waste-based feedstocks, namely, OPL (oil palm leaf), PKS (palm kernel shell), and EFB (empty fruit bunch). Here, the electrochemical measurements of the resulting reduced graphene oxides derived via mild-temperature annealing reduction of the graphene oxides were accomplished using cyclic voltammetry and galvanostatic charge/discharge processes. The findings put forward their promising features for supercapacitor applications. For instance, the reduced graphene oxide derived using EFB precursor (rGOEFB) which has a BET surface area of 117 m2 g-1 exhibits a specific capacitance of 688 F g−1 at an applied current density of 0.8 A g-1. This is higher than that observed for reduced graphene oxides derived from oil palm leaf (rGOOPL), palm kernel shell (rGOPKS), and the commercially acquired graphite (rGOCG), which possessed specific capacitance values of 632, 424, and 220 F g−1, respectively. It can be deduced that the specific capacitance of the reduced graphene oxide samples increases in the following order: (rGOCG) < (rGOPKS) < (rGOOPL) < (rGOEFB). In summary, these new classes of carbon-based nanomaterials could be applied as efficient electrode materials for supercapacitor application with potential good performance. With this novel green and sustainable approach, various carbon-based nanomaterials can be fabricated for a broad range of multifunctional applications.
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Habte, Adere Tarekegne, e Delele Worku Ayele. "Synthesis and Characterization of Reduced Graphene Oxide (rGO) Started from Graphene Oxide (GO) Using the Tour Method with Different Parameters". Advances in Materials Science and Engineering 2019 (15 agosto 2019): 1–9. http://dx.doi.org/10.1155/2019/5058163.
Testo completoAbstract (sommario):
A new approach to synthesize graphene is oxidizing graphite powder with a mixture of H2SO4/H3PO4 acids and potassium permanganate. Parameters such as reaction time, reaction temperature, and amount of concentration were varied to study the degree of oxidation of graphite to graphene oxide. Currently, an improved method for the preparation of graphene oxide was the most common one. A mixture of H2SO4/H3PO4 (9 : 1 volume ratio) instead of only H2SO4 resulted in increased hydrophilic and oxidized GO without the emission of toxic gas, which differs from the traditional Hummers’ method. The graphene oxide (GO) was converted to reduced graphene oxide (rGO) by chemical reduction using ascorbic acid as the reducing agent. The GO and rGO were characterized by UV-visible spectroscopy, FTIR spectroscopy, and X-ray diffraction patterns. The result showed that treating graphite powder with potassium permanganate (1 : 9) and a mixture of concentrated H2SO4/H3PO4 acids at 50°C for 12 hours resulted in a better oxidation degree. The designed synthesis strategy could be easily controlled and is an alternative green approach for the production of graphene oxide and reduced graphene oxide.
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Ramirez-Barria, Carolina S., Diana M. Fernandes, Cristina Freire, Elvira Villaro-Abalos, Antonio Guerrero-Ruiz e Inmaculada Rodríguez-Ramos. "Upgrading the Properties of Reduced Graphene Oxide and Nitrogen-Doped Reduced Graphene Oxide Produced by Thermal Reduction toward Efficient ORR Electrocatalysts". Nanomaterials 9, n. 12 (11 dicembre 2019): 1761. http://dx.doi.org/10.3390/nano9121761.
Testo completoAbstract (sommario):
N-doped (NrGO) and non-doped (rGO) graphenic materials are prepared by oxidation and further thermal treatment under ammonia and inert atmospheres, respectively, of natural graphites of different particle sizes. An extensive characterization of graphene materials points out that the physical properties of synthesized materials, as well as the nitrogen species introduced, depend on the particle size of the starting graphite, the reduction atmospheres, and the temperature conditions used during the exfoliation treatment. These findings indicate that it is possible to tailor properties of non-doped and N-doped reduced graphene oxide, such as the number of layers, surface area, and nitrogen content, by using a simple strategy based on selecting adequate graphite sizes and convenient experimental conditions during thermal exfoliation. Additionally, the graphenic materials are successfully applied as electrocatalysts for the demanding oxygen reduction reaction (ORR). Nitrogen doping together with the starting graphite of smaller particle size (NrGO325-4) resulted in a more efficient ORR electrocatalyst with more positive onset potentials (Eonset = 0.82 V versus RHE), superior diffusion-limiting current density (jL, 0.26V, 1600rpm = −4.05 mA cm−2), and selectivity to the direct four-electron pathway. Moreover, all NrGOm-4 show high tolerance to methanol poisoning in comparison with the state-of-the-art ORR electrocatalyst Pt/C and good stability.
41
NAEEM, Nida, Mudassar ABBAS e Mumtaz Hasan MALIK. "GRAPHENE/GRAPHENE OXIDE BASED COATINGS FOR ADVANCED TEXTILE APPLICATIONS". TEXTEH Proceedings 2019 (5 novembre 2019): 148–52. http://dx.doi.org/10.35530/tt.2019.31.
Testo completoAbstract (sommario):
Today, graphene oxide has been significantly used in many technological sectors, medical sectors as well in textiles due to its abundant applications and dominant characteristics. Graphene oxide is basically a mono layered material synthesized by the oxidation of graphite by the addition of multiple functional groups containing oxygen such as alcohols, carboxylic acids and epoxides and presenting a 2-diamentional honeycomb structure. On the textile surfaces the grapheme oxide can be applied through Pad dry-cure, Dip dry-cure and Spray coating methods. However, the most appropriate method is dipping of the fabric into the graphene suspension and the process is followed by drying and curing techniques. Initially, the fabric swatches have been cut out in a suitable size according to the padder or adjustments on the machine can also be done. 100% pure cotton, polyester, cotton polyester blend, silk, aramids and acrylics have been used as a substrate for the application of graphene to imparts different functional properties. The oxygen content is reduced resulting the increase in the interlayer spacing’s well as functionalization. The oxygen containing groups have been removed with the repossession of the conjugated structure. The reduced graphene oxide has the higher strength as well as high electrical and thermal conductivity which effect the final performance of a materials.
42
Wang, Ziming, Yiyang Cao, Decai Pan e Sen Hu. "Vertically Aligned and Interconnected Graphite and Graphene Oxide Networks Leading to Enhanced Thermal Conductivity of Polymer Composites". Polymers 12, n. 5 (14 maggio 2020): 1121. http://dx.doi.org/10.3390/polym12051121.
Testo completoAbstract (sommario):
Natural graphite flakes possess high theoretical thermal conductivity and can notably enhance the thermal conductive property of polymeric composites. Currently, because of weak interaction between graphite flakes, it is hard to construct a three-dimensional graphite network to achieve efficient heat transfer channels. In this study, vertically aligned and interconnected graphite skeletons were prepared with graphene oxide serving as bridge and support via freeze-casting method. Three freezing temperatures were utilized, and the resulting graphite and graphene oxide network was filled in a polymeric matrix. Benefiting from the ultralow freezing temperature of −196 °C, the network and its composite occupied a more uniform and denser structure, which lead to enhanced thermal conductivity (2.15 W m−1 K−1) with high enhancement efficiency and prominent mechanical properties. It can be significantly attributed to the well oriented graphite and graphene oxide bridges between graphite flakes. This simple and effective strategy may bring opportunities to develop high-performance thermal interface materials with great potential.
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Piñas, Jean A. V., Tatiana S. Andrade, Andreia T. Oliveira, Pedro E. A. Salomão, Mariandry Rodriguez, Adilson C. Silva, Henrique S. Oliveira, Douglas S. Monteiro e Márcio C. Pereira. "Production of Reduced Graphene Oxide Platelets from Graphite Flakes Using the Fenton Reaction as an Alternative to Harmful Oxidizing Agents". Journal of Nanomaterials 2019 (9 gennaio 2019): 1–8. http://dx.doi.org/10.1155/2019/5736563.
Testo completoAbstract (sommario):
The conventional chemical methods to produce graphene using strong oxidizing agents produce toxic gases during synthesis; therefore, these methods do not meet the principles of green chemistry. In this work, an alternative top-down method for the synthesis of a few layers of graphene sheets has been produced by a Fenton reaction- (a mixture of Fe2+/H2O2) assisted exfoliation process in water using graphite flakes as a starting material. Based on X-ray diffraction data and Fourier transform infrared (FTIR), Raman spectroscopy, and transmission electron microscopy measurements, it is proposed that the oxidation of graphite by Fenton chemistry facilitates the exfoliation of graphene sheets under mild sonication. Subsequent chemical reduction with ascorbic acid produced a few layers of reduced graphene oxide. Compared to Hummers’ method, the Fenton reagent has similar exfoliation efficiency, but due to the Fenton reagent’s preference to react with the edges of graphite, the chemical reduction can lead to the formation of less defective reduced graphene oxides. Moreover, since Fe and H2O2 are cheap and environmentally innocuous, their use in large-scale graphene production is environmentally friendlier than conventional methods that use toxic oxidizing agents.
44
Soni, Jay, Ayushi Sethiya, Nusrat Sahiba, Mahendra Singh Dhaka e Shikha Agarwal. "New Insights into the Microstructural Analysis of Graphene Oxide". Current Organic Synthesis 18, n. 4 (7 giugno 2021): 388–98. http://dx.doi.org/10.2174/1570179418666210113162124.
Testo completoAbstract (sommario):
Aim and Objective: To explore the impact of synthesis conditions (temperature and time) on the properties of developed Graphene Oxide (GO). Background: A highly promising approach has been used for the synthesis of graphene oxide (GO) from graphite flakes using the modified Hummers method. Concentrated sulfuric acid was used as an intercalating agent and the oxidation was done with the help of potassium permanganate and hydrogen peroxide. Methods: The present method does not need expensive membranes for the filtration of Carbon and metalcontaining residues. The pre-cooling method is used to eradicate the explosive behavior of intermediate steps. The high quality of synthesized graphene oxides was confirmed by a series of characterization techniques, including Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, thermogravimetric analysis, energy-dispersive X-ray spectroscopy, and atomic force microscopy. Results: The results indicated the presence of Oxygen-containing functional groups, and a rise in the Oxygen content confirmed the synthesis of high-quality graphene oxide. Conclusion: As per obtained experimental findings and subsequent analysis, the synthesized high-quality graphene oxide could be used in the design of membranes for water treatment applications.
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Huang, Qiao, Hong Juan Sun e Tong Jiang Peng. "The Influence of Temperature and Oxidation Time on the Preparation of Graphite Oxide". Advanced Materials Research 366 (ottobre 2011): 291–95. http://dx.doi.org/10.4028/www.scientific.net/amr.366.291.
Testo completoAbstract (sommario):
Graphite oxide samples with different oxidation levels were prepared by the oxidation of natural flake graphite based on a modified Hummers method, using different reaction temperatures and oxidation times followed by ultrasonication then centrifugation to obtain the corresponding graphene oxide nanosheet suspensions. The samples were characterized by XRD and AFM. The results show that the oxidation level of graphite oxide samples can be increased by increasing either the reaction temperature or the oxidation time. Well-dispersed suspensions of the graphite oxide samples can be formed in alkaline solution after ultrasonication, especially for samples with higher oxidation levels. A number of coarse particles are observed in the suspensions, particularly those derived from graphite oxide samples with lower oxidation levels, due to the lower degree of exfoliation in these samples, which is influenced by the oxidation level. Rapid sedimentation of these coarse particles can be achieved by high-speed centrifugation, yielding homogenous suspensions of graphite oxide comprising a mass of monolayer graphene oxide nanosheets with lateral dimensions of several hundred nanometers to several micrometers and thickness of ~1.0–1.4 nm.
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T, Remyamol, Pramod Gopinath e Honey John. "Phenylenediamine functionalized reduced graphene oxide/polyaniline hybrid: synthesis, characterization, improved conductivity and photocurrent generation". RSC Adv. 4, n. 56 (2014): 29901–8. http://dx.doi.org/10.1039/c4ra03155e.
Testo completoAbstract (sommario):
Phenylenediamine functionalized reduced graphene oxide (GONH2) is designed and synthesized for the preparation of a polyaniline/reduced graphene oxide hybrid having better interactions than that of the unfunctionalized graphite oxide/polyaniline hybrid.
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Mochizuki, Tomofumi, Yamato Hayashi, Jun Fukushima e Hirotsugu Takizawa. "Synthesis and Characterization of Ag/Graphene Nanocomposites by Solid-Liquid Sonochemical Reactions". Materials Science Forum 804 (ottobre 2014): 119–22. http://dx.doi.org/10.4028/www.scientific.net/msf.804.119.
Testo completoAbstract (sommario):
In this study, Graphite Oxide (GO) and Ag/Graphene nanocomposites were synthesized by solid-liquid sonochemical reactions easily and briefly. GO was synthesized by means of Hummers method using sonication or stirring. From XRD patterns and FT-IR spectra, chemical and physical effects of ultrasound promoted the oxidation of Graphite. Ag/graphene nanocomposites were synthesized from GO and silver oxide by sonication. UV-vis spectra showed the peaks of Graphene oxide and Ag nanoparticle plasmon resonance absorption. EDX images and electron diffraction patterns confirmed Ag nanoparticles were decorated on Graphene sheets by ultrasound. Using sonication, GO and Ag/Graphene nanocomposites could be synthesized easily in short time.
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Kawata, Kazunori, Syunsuke Kawaki, Takako Nakamura, Yoshinori Koga e Masataka Hasegawa. "Fabrication of multi-layer graphene by repeated transfer". AIP Advances 12, n. 9 (1 settembre 2022): 095110. http://dx.doi.org/10.1063/5.0100501.
Testo completoAbstract (sommario):
Multi-layer graphene was formed by repeated transfer onto a silicon oxide substrate, and changes in its doping characteristics were observed. The structure of multi-layer graphene was investigated in comparison with pyrolytic graphite with a turbostratic structure. Single-layer graphene is doped due to the influence of the silicon oxide substrate, and the influence of poly(methyl methacrylate) and water residue, which are used for the transfer, is small. Graphene in the first layer suppresses the influence of the silicon oxide substrate, and the second and subsequent layers are almost unaffected. By repeating the transfer and stacking, multi-layer graphene approaches ideal turbostratic graphite.
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KANBUR, Kürşat, Işıl BİRLİK, Fatih SARGIN, N. Funda AK AZEM e Ahmet TÜRK. "INVESTIGATION THE EFFECT OF pH VALUE IN GRAPHENE OXIDE PRODUCTION". Euroasia Journal of Mathematics, Engineering, Natural & Medical Sciences 9, n. 20 (25 marzo 2022): 189–97. http://dx.doi.org/10.38065/euroasiaorg.944.
Testo completoAbstract (sommario):
In recent years, the use of graphene oxide (GO) in advanced application areas has attracted great interest. GO consists of a carbon basal plane containing various functional groups. Thanks to its properties, GO can improve the properties of the materials to which it is added. Therefore, GO is used in various photocatalytic, sensor and battery applications. Moreover, large-scale production of graphene, which has outstanding propertiessuch as high electrical conductivity, thermal conductivity, and high surface area, is possible by reduction of GO. Therefore, quality and controllable GO production is required. GO is generally produced with the Hummer's Method, which is a suitable chemical method for industrial production. In Hummer's Method, graphite oxide is obtained by oxidizing of graphite with the help of oxidizing agents. Afterwards, GO is obtained by exfoliating of the graphite oxide. However, the original Hummer Method has many disadvantages due to the emission of harmful, dangerous gases and its low efficiency. Many Hummer's methods have been derived by researchers from past to present. As a result of various modifications, the Modified Hummer's Method, which includes efficient, non-toxic and harmless production method steps, was preferred in GO production. Each stage of production process affects the properties and structures of the obtained GO. Understanding the effect of GO production parameters on GO structure, is important for its use in electronics, optics, biological, and graphene production applications. In Hummer's Method, after the oxidation of graphite, washing with HCl followed by distilled water is applied to remove impurities. The final step, which is the washing process, is an important step for the final structure properties of GO. In this study, the effect of pH value on the obtained GO structure was investigated by using the Modified Hummer's Method that we developed. Structural characterization studies of GO samples from solutions at different pH levels were performed using X-Ray Diffractometry (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and Ultraviolet - Visible Spectrophotometer (UV-Vis). According to the obtained results, it was determined that the difference in pH level of solution changed the structure of GO and affected the degree of exfoliation. Keywords: Graphene oxide, pH, Purification, Modified Hummer’s, XRD, FTIR.
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Lei, Lin, Jian Hui Qiu, Xue Li Wu, Yang Zhao e Eiichi Sakai. "Graphene-Poly(Methyl Methacrylate) Composites Prepared by Two Methods". Advanced Materials Research 335-336 (settembre 2011): 49–53. http://dx.doi.org/10.4028/www.scientific.net/amr.335-336.49.
Testo completoAbstract (sommario):
Graphene-poly(methyl methacrylate) (GNS-PMMA) composites were prepared by two methods. Graphite oxide nanosheet-poly(methyl methacrylate) (GO-PMMA) composites were prepared of methyl methacrylate monomer and the presence of graphite oxide (GO). Then the GO-PMMA composites were reduced to graphene nanosheet-poly(methyl methacrylate) by using hydrazine hydrate. The obtained composites were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and Transmission electron microscopy (TEM). The composite exhibited conductivities in the 1.58×10-9-4.21 S/cm range, depending on the amounts of graphite oxide and PMMA.