Synthesis of Graphene Oxide (GO) by Modified Hummers Method and Its Thermal Reduction to Obtain Reduced Graphene Oxide (rGO)
Synthesis of Graphene Oxide (GO) by Modified Hummers Method and Its Thermal Reduction to Obtain Reduced Graphene Oxide (rGO)
复制标题
DOI：
10.4236/graphene.2017.61001
复制
发表时间：
2017-01
期刊：
影响因子：
--
通讯作者：
S. N. Alam;Nidhi Sharma;L. Kumar
中科院分区：
文献类型：
--
作者：
S. N. Alam;Nidhi Sharma;L. Kumar
多年来，人们不断追求对石墨烯的各种合成方法的改进，以提供更安全和更有效的替代品。虽然通过Hummers方法提取石墨烯是最古老的技术之一，但它是形成块状石墨烯的最合适的方法之一。石墨烯可以以还原的氧化石墨的形式获得，有时也称为氧化石墨烯。该氧化过程的有效性可以通过所获得的石墨烯的碳/氧比的大小来评估。在此，氧化石墨烯（GO）通过由改进的Hummers方法氧化纯化的天然鳞片石墨（NFG）来制备。已经尝试通过使用改进的Hummers方法合成具有较少层的GO，其中减少了NaNO 3的量，并且增加了KMnO 4的量。反应在9：1（体积比）的H2SO 4/H3 PO 4混合物中进行。这种改进是成功的，在提高反应产率和减少有毒气体的释放，同时使用不同比例的KMnO 4和H2SO 4所需的Hummers方法。在反应体系中引入了一种新的组分K_2S_2O_8，以保持体系的pH值。还原的氧化石墨烯（rGO）随后通过GO的热改性来提取。在这里，GO已被用作通过热还原工艺合成石墨烯的前体。红外光谱和拉曼光谱分析表明，NFG经KMnO 4和NaNO 3等强氧化剂氧化后，在石墨层中引入了氧原子，并与石墨层中的碳原子形成了C=O、C-H、COOH和C-O-C等键。采用X射线衍射（XRD）、扫描电子显微镜（SEM）、高分辨透射电子显微镜（HR-TEM）、傅里叶变换红外光谱（FTIR）、紫外-可见光谱、拉曼光谱、BET比表面积分析、差示扫描量热分析（DSC）和热重分析（TGA）对GO和rGO的结构和形貌进行了分析。
Over the span of years, improvements over various synthesis methods of graphene are constantly pursued to provide safer and more effective alternatives. Though the extraction of graphene through Hummers method is one of the oldest techniques yet it is one of the most suitable methods for the formation of bulk graphene. Graphene can be obtained in the form of reduced Graphite oxide, sometimes also referred as Graphene oxide. The effectiveness of this oxidation process can be evaluated by the magnitude of carbon/oxygen ratio of the obtained graphene. Here, graphene oxide (GO) was prepared by oxidizing the purified natural flake graphite (NFG) by a modified Hummers method. The attempts have been made to synthesize GO having few layers by using a modified Hummers method where the amount of NaNO3 has been decreased, and the amount of KMnO4 is increased. The reaction has been performed in a 9:1 (by volume) mixture of H2SO4/H3PO4. This modification is successful in increasing the reaction yield and reducing the toxic gas evolution while using a varied proportion of KMnO4 and H2SO4 as those required by Hummers method. A new component of K2S2O8 has been introduced to the reaction system to maintain the pH value. Reduced graphene oxide (rGO) was thereafter extracted by thermal modification of GO. Here, GO has been used as a precursor for graphene synthesis by thermal reduction processes. The results of FTIR and Raman spectroscopy analysis show that the NFG when oxidized by strong oxidants like KMnO4 and NaNO3, introduced oxygen atoms into the graphite layers and formed bonds like C=O, C-H, COOH and C-O-C with the carbon atoms in the graphite layers. The structure and morphology of both GO and rGO were analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR-TEM), Fourier transform infrared spectroscopy (FTIR), ultraviolet-visible spectroscopy, Raman spectroscopy, Brunauer-Emmett-Teller (BET) surface area analysis and differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA).