共查询到19条相似文献,搜索用时 125 毫秒
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采用Hummers法,在浓硫酸、高锰酸钾等氧化剂存在条件下,将石墨粉氧化制备成氧化石墨烯,将氧化石墨溶解于水中,然后用水合肼还原氧化石墨烯后制备得到石墨烯,同时,采用红外光谱、紫外光谱、透射电镜等手段对得到的氧化石墨烯和石墨烯进行了表征。结果表明:制备得到了氧化石墨烯和石墨烯,且二者已经充分剥离。 相似文献
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通过插层硫酸催化氧化石墨脱水制备高比电容石墨烯。低温加热条件下,经过氧化石墨中嵌入的硫酸催化作用,氧化石墨会迅速脱水和脱去羧基而剥离和还原生成功能化石墨烯。这种制备石墨烯的方法,可简单快速地制备大量功能化石墨烯材料。这种表面功能化的石墨烯具有较高的电化学容量,在1mol/L的 H2SO4溶液中,以0.5A/g的电流密度充放电时,电化学容量高达226F/g。 相似文献
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石墨烯因其独特的二维结构和优异的物理性能在众多领域中引起了广泛的关注,高质量石墨烯的制备是实现其应用价值的前提。尽管目前石墨烯的制备方法较多,但是开发绿色、低成本、规模化制备方法的道路仍然充满挑战。物理法剥离石墨能够实现高结晶石墨烯的制备,特别是超临界CO2流体具有廉价、绿色、稳定、易分离且可重复利用的优势,在石墨烯制备上展现出巨大的应用潜力。以超临界CO2制备石墨烯为出发点,梳理了近年来超临界CO2法剥离石墨制备石墨烯的研究进展,重点阐述了制备过程中的强化剥离手段,期望对未来石墨烯材料的制备提供思路。 相似文献
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石墨烯的制备与表征 总被引:8,自引:0,他引:8
采用液相氧化法制备了氧化石墨,并通过水合肼还原氧化石墨制备了石墨烯。采用傅里叶变换红外光谱(FT-IR)、拉曼光谱(RS)、X-射线衍射(XRD)、热失重法(TG)等测试方法对石墨、氧化石墨和石墨烯的结构与耐热性进行了对比分析。研究结果表明,氧化石墨被水合肼还原成石墨烯后,氧化石墨的一部分sp3杂化碳原子被还原成石墨的sp2杂化碳原子,石墨烯sp2杂化碳层平面的平均尺寸比氧化石墨大,但结晶强度和规整度比石墨有所降低。在本实验条件下,氧化石墨的还原状态结构不可能被完全恢复到原有的石墨状态,也就是说石墨烯的结构和石墨结构还是有差别的。热分析结果表明,石墨烯具有比氧化石墨更为优异的热稳定性。 相似文献
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《Carbon》2014
One-step synthesis of high quality graphene at gram-scale quantities is important for industrial applications, e.g. in electrochemistry for sensing and energy storage. Currently, thermal reduction/exfoliation of graphite oxide (GO) is a typical method of choice. However, it has the drawback of requiring specialized equipment for rapid thermal shock. A recent alternative method, microwave-assisted exfoliation, usually suffers from poor reduction of graphite oxide and thus low C/O ratios. Herein we show that vacuum-assisted microwave reduction/exfoliation of graphite oxide in a closed system leads to high C/O ratios and partial hydrogenation of graphene (2.6 at.% of H). Microwave irradiation of graphite oxide in vacuum leads to outgassing from GO and the creation of plasma which aids temperature distribution and hydrogenation. This plasma is quickly extinguished by further dramatic evolution of gases from GO and consequent pressure increase. We assess the influence of precursor graphite oxide, prepared by Hummers, Staudenmaier, and Hofmann methods, upon the materials properties of microwave exfoliated graphene. We show that microwave-exfoliated graphenes prepared from different graphite oxides show very fast heterogeneous electron transfer rates, with similar electrochemical behaviour to thermally reduced graphene oxide. 相似文献
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Zhenggang Luo Huijian Ye Jiawei Hu Te Hu Boyuan Zhang Xuanhe Zhang Lixin Xu 《应用聚合物科学杂志》2020,137(43):49320
A strategy for preparing ethylene-vinyl acetate (EVA)/graphene nanocomposites from liquid-phase exfoliated graphene has been explored with the use of a pyrene-functionalized hyperbranched polyethylene (HBPE) ternary copolymer, HBPE@Py@PMA, as stabilizer for graphite exfoliation. The HBPE@Py@PMA was synthesized by combining the Pd-diimine-catalyzed chain walking ternary ethylene copolymerization and atomic transfer radical polymerization techniques and has been confirmed to possess a HBPE core simultaneously bearing pyrene terminal groups and polymethacrylate side chains. As stabilizer, it is found to effectively promote graphite exfoliation in CHCl3 to render high-quality few-layer graphene with an efficiency as high as 43%. Meanwhile, it can be steadily adsorbed on the exfoliated graphene surface to concurrently render functionalized graphene well dispersible in EVA matrix with strong interfacial interactions. This allows us to obtain EVA/graphene nanocomposites from resulting graphene dispersion through simple solution mixing process. By adding only 0.5 wt% of graphene, the dielectric constant of resulting composite increases by 55% compared to pure EVA, with a dielectric loss only 0.012. The role mechanism of the HBPE@Py@PMA for promoting graphite exfoliation in CHCl3 and the formation of EVA/graphene nanocomposites from the resulting graphene has been proposed. 相似文献
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Qinglai Du 《Electrochimica acta》2010,55(12):3897-203
Two kinds of functionalized graphene sheets were produced by thermal exfoliation of graphite oxide. The first kind of functionalized graphene sheets was obtained by thermal exfoliation of graphite oxide at low temperature in air. The second kind was prepared by carbonization of the first kind of functionalized graphene sheets at higher temperature in N2. Scanning electron microscopy images show that both two kinds of samples possess nanoporous structures. The results of N2 adsorption-desorption analysis indicate that both of two kinds of samples have high BET surface areas. Moreover, the second kind of functionalized graphene sheets has a relatively higher BET surface area. The results of electrochemical tests is as follows: the specific capacitance values of the first kind of functionalized graphene sheets in aqueous KOH electrolyte are about 230 F g−1; the specific capacitance values of the second kind of functionalized graphene sheets with higher BET surface areas are only about 100 F g−1; however, compared with the first kind of functionalized graphene sheets, the second kind has a higher capacitance retention at large current density because of its good conductive behaviors; furthermore, in non-aqueous EC/DEC electrolyte, the specific capacitance values of the first kind sample and the second kind sample are about 73 F g−1 and 36 F g−1, respectively. 相似文献
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In situ preparation of graphene‐ZnO composites for enhanced graphite exfoliation and graphene‐nylon‐6 composite films 下载免费PDF全文
An effective method for the fabrication of graphene‐ZnO nanoparticle (GZN) composites has been developed. GZN composites with high electrical conductivity (18,607 S/m) are prepared in situ from graphite‐ZnO composites. The GZN composites also exhibit visible‐light absorption and enable the effective exfoliation of graphite. The presence of the ZnO nanoparticles assists the exfoliation of graphite and enables the preparation of solutions of highly dispersed and concentrated graphene sheets (2.7 mg/mL) that exhibit high electrical conductivity without reduction (40,404 S/m). A solution of graphene sheets was used to produce a graphene‐nylon‐6 film with an excellent Young's modulus (3 GPa) and a high tensile strength (109 MPa). An exclusive mechanism was proposed for the improvement of mechanical properties of the nylon‐6 composite film. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45034. 相似文献
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Although easily scalable, the production of graphene nanoplatelets (GNP) by the means of liquid-phase exfoliation of graphite flakes (GF) remains an energy- and time-intensive process. In this work, we demonstrate that significant time and energy can be saved in GNP production when employing expanded graphite (EG) in a surfactant-assisted liquid phase exfoliation process. Owing to its increased interlayer distance, the exfoliation of EG can be accomplished in a much shorter time (<30 min) compared to GF (approximately 7 h in the present case). Moreover, the energy required for the EG exfoliation is close to 80-fold lower than that for GF exfoliation. Monitoring of the mean lateral dimension, specific surface area, and graphite flake-to-GNP transition during exfoliation was performed experimentally using several analytical techniques. The EG-derived GNPs are produced much faster and require less energy for exfoliation compared to GF, thus making it a more efficient alternative technique. 相似文献
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Burcu Saner 《Fuel》2010,89(8):1903-25218
An improved, safer and mild method was proposed for the exfoliation of graphene like sheets from graphite to be used in fuel cells. The major aim in the proposed method is to reduce the number of layers in the graphite material and to produce large quantities of graphene bundles to be used as catalyst support in polymer electrolyte membrane fuel cells. Graphite oxide was prepared using potassium dichromate/sulfuric acid as oxidant and acetic anhydride as intercalating agent. The oxidation process seemed to create expanded and leafy structures of graphite oxide layers. Heat treatment of samples led to the thermal decomposition of acetic anhydride into carbondioxide and water vapor which further swelled the layered graphitic structure. Sonication of graphite oxide samples created more separated structures. Morphology of the sonicated graphite oxide samples exhibited expanded the layer structures and formed some tulle-like translucent and crumpled graphite oxide sheets. The mild procedure applied was capable of reducing the average number of graphene sheets from 86 in the raw graphite to nine in graphene-based nanosheets. Raman spectroscopy analysis showed the significant reduction in size of the in-plane sp2 domains of graphene nanosheets obtained after the reduction of graphite oxide. 相似文献
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《Carbon》2013
In this paper we demonstrate that the yield and size of the graphene oxide sheets (GO) obtained by sonication of graphite oxide (GrO) can be optimized not only by selecting the appropriate exfoliation conditions but also as a function of the crystalline structure of the parent graphite. A larger crystal size in the parent graphite favors GrO exfoliation and yields larger sheets in shorter sonication times, independently of the oxygen content of the GrO. A maximum yield of GO is obtained in all cases, after which no further improvement is achieved and the size of the sheets decreases. 相似文献
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《Ceramics International》2019,45(10):13409-13413
We report an industrially viable promising approach to produce micrometer-sized multilayer graphene nanoplatelet powder (MGNP) in a scalable quantity via microwave-assisted exfoliation of graphite (MEG) and fragmented into MGNP through liquid-phase exfoliation in the co-solvent mixture by kitchen mixer (KM). KM allows rapid delaminating MEG into MGNP by shear force dominated exfoliation. Majority of MGNPs are with a diameter of few micrometers and thickness is in nanometers. MGNP are crystalline with very limited defects was confirmed by Raman measurements and transmission electron microscopy. This process transforms, more than 86% of graphite flakes into MGNP. This advanced approach opens a new pathway to produce MGNP in bulk quantity as it is feasible, rapid, and cost-effective. 相似文献
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采用Hummers法合成氧化石墨,通过超声分散法获得氧化石墨烯,并使用溶剂蒸发法制备了氧化石墨烯/聚偏氟乙烯复合膜。采用透射电子显微镜(TEM)、红外光谱(FTIR)以及X射线衍射(XRD)对氧化石墨烯的形貌和结构进行分析,对复合膜进行扫描电子显微镜(SEM)、机械性能以及导热系数的分析测定。结果表明,本实验中制备的氧化石墨烯含有大量的含氧基团;氧化石墨烯能够均匀的分散在复合膜中,并且会增加复合膜的机械性能和导热性能。复合膜的导热系数随w(氧化石墨烯)的增加而呈现先增大后减小的趋势,当w(氧化石墨烯)为0.4%时,导热系数达到最大值。 相似文献