Simple Synthesis of Large Graphene Oxide Sheets via Electrochemical Method Coupled with Oxidation Process
Simple Synthesis of Large Graphene Oxide Sheets via Electrochemical Method Coupled with Oxidation Process
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DOI：
10.1021/acsomega.8b01283
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发表时间：
2018-08-01
期刊：
影响因子：
4.1
通讯作者：
Srivastava, Vimal Chandra
中科院分区：
文献类型：
--
作者：
Kumar, Navneet;Srivastava, Vimal Chandra
在本文中，我们报告了一种简单的两步法合成横向尺寸约为10 μ m或更大的大型氧化石墨烯（GO）片。第一步是预处理步骤，涉及在H2SO 4和H3 PO 4的混合物中电化学剥离石墨电极以产生石墨烯。第二步是氧化步骤，其中使用KMnO 4作为氧化剂进行剥离的石墨烯片的氧化。氧化在类似于60 ℃下进行1至12小时的不同时间。制备的GO批料使用许多光谱和显微镜技术表征，例如X射线衍射（XRD）、场发射扫描电子显微镜（FE-SEM）、透射电子显微镜（TEM）、傅里叶变换红外光谱（FTIR）和UV可见光谱。使用拉曼和热重分析技术来研究所合成的GO批料中的氧化程度。紫外可见吸收光谱在230 nm处显示出强峰，在300 nm处显示出相邻的带，对应于所有样品中的pi-pi* 和n-pi* 跃迁。使用归一化的FTIR图来计算含氧官能团的相对百分比，发现其在GO（6 h）中最大。使用Boehm滴定来定量GO表面上存在的官能团。发现在6小时氧化后获得的总体GO片（GO（6小时））是最好的。GO（6小时）的XRD图案显示在2 θ = 8.88度处的特征峰，其中层之间的相应晶面间距为0.995 nm，这相对于文献中报道的先前方法是最好的。拉曼光谱显示，GO（6 h）的缺陷度（I-D/I-G）面积比为1.24，这高于通过广泛使用的Marcano方法制备的GO（1.18）获得的缺陷度。
In this paper we report a simple two-step approach for the synthesis of large graphene oxide (GO) sheets with lateral dimensions of approximate to 10 mu m or greater. The first step is a pretreatment step involving electrochemical exfoliation of graphite electrode to produce graphene in a mixture of H2SO4 and H3PO4. The second step is the oxidation step, where oxidation of exfoliated graphene sheets was performed using KMnO4 as the oxidizing agent. The oxidation was carried out for different times ranging from 1 to 12 h at similar to 60 degrees C. Prepared GO batches were characterized using a number of spectroscopy and microscopy techniques such as X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FTIR), and UV visible spectroscopy. Raman and thermogravimetric analysis techniques were used to study the degree of oxidation in the as-synthesized GO batches. The UV visible absorption spectrum showed an intense peak at 230 nm and an adjacent band at 300 nm corresponding to pi-pi* and n-pi* transitions in all samples. Normalized FTIR plots were used to calculate the relative percentages of oxygen-containing functional groups, which were found to be maximum in GO (6 h). Boehm titration was used to quantify the functional groups present on the GO surface. Overall GO sheets obtained after 6 h of oxidation, GO (6 h), were found to be the best. XRD pattern of GO (6 h) revealed a characteristic peak at 2 theta = 8.88 degrees, with the corresponding interplanar spacing between the layers being 0.995 nm, which is among the best with respect to the previous methods reported in the literature. Raman spectroscopy showed that the degree of defect (I-D/I-G) area ratio for GO (6 h) was 1.24, which is higher than that obtained for GO (1.18) prepared by widely used Marcano's approach.