【作者】 陈翠红；

【导师】 刘雪芹；

【作者基本信息】 兰州大学 ， 凝聚态物理， 2010， 硕士

【摘要】 石墨烯(graphene)是迄今为止世界上最薄的一种新型二维碳材料。石墨烯具有高的载流子迁移率,其电子具有亚微米尺度的弹道传输特性,常温下具有极快的电子传输速率,这些优异的性质使得它在纳米电子器件方面具有广泛的应用前景。本文主要采用撕胶带法和氧化还原法制备了少层石墨,并通过Raman光谱对样品进行了系统研究。利用高定向热解石墨(HOPG)优异的层状结构,通过反复撕胶带法分别在300nm SiO2/Si和Si衬底上得到了少层石墨。通过不同厚度样品的Raman光谱对比,可以辨别出少层石墨；从光学显微图片看,少层石墨在300nm SiO2/Si衬底上的光学对比度更好,通过Raman光谱测试也证实了这点,并在300nm SiO2/Si衬底上获得了单层石墨,即石墨烯。以高纯石墨粉为原料,利用改进的Hummers法制备得到了氧化石墨(GO),样品的Raman光谱测试显示：氧化后石墨的2D峰消失,D峰与G峰变宽,且强度比变大,表明其结构发生了变化,缺陷增多。XRD测试结果显示,石墨的(002)峰消失,GO的(100)和(001)衍射峰出现,表明石墨被氧化了。分别采用高压釜热还原和水合肼化学还原对GO进行了还原,通过Raman光谱分析得出：(1)石墨2D峰的重新出现表明GO的结构发生了变化。(2)通过ID/IG值的比较,可以得出高压釜热还原方法在一定程度上对石墨氧化过程中产生的缺陷进行了修复,还原效果优于水合肼还原。XRD测试显示石墨(002)特征衍射峰增强,GO的(100)和(001)衍射峰减弱,GO被还原。还原产物在水中和NMP中的分散性研究表明还原后GO中的亲水基团大量消失。GO及其还原产物的PL谱测试显示,GO粉末发绿光,还原产物发蓝光,这也说明GO还原后结构发生了变化。Raman光谱是一种无损的、快速的、准确的判断石墨烯的有效手段,在GO及还原产物的结构表征方面也具有重要的意义。更多还原

【Abstract】 Graphene is the thinnest known material in the universe and the strongest ever measured. Its charge carriers exhibit giant intrinsic mobility, and can travel for micrometers without scattering at room temperature. These unique properties hold great promise for potential applications in nanoelectronics. In this paper, few-layer graphene was prepared by micromechanical cleavage and reduction of GO, respectively. The structure of the sample were characterized systemly by Raman spectroscopy.Single- and few-layer graphene taken from freshly cleaved HOPG surfaces by the scotch-tape technique can be readily transferred on to silicon wafer. It is interesting that single-layer graphene placed on a Si wafer with a 300nm thick layer of SiO2 becomes visible in an optical microscope. Results of Raman and optical microscopy measurement showed that few-layer graphene was presence.GO were produced using a modified Hummers’ method from high-purity graphite powder. It was found that graphite were oxided completely, which was demonstrated by Raman spectroscopy and XRD. Dispersions of GO was carried out in water and NMP, respectively. It was found that GO can be dispersed uniformly.Herein, hydrothermal dehydration by using of teflonlined autoclave and hydrazine were used to reduced GO. It is found that hydrothermal dehydration had a better effect on reduction of GO compared to hydrazine. Dispersions of GO-reduced was also carried out in water and NMP, respectively. It was found that GO-reduced can not be dispersed in warer by bath ultrasonication and it may be because of hydrophilic groups’ absent on GO.PL spectra of the sample showed that the luminescence of GO and GO-reduced were found to occur in the visible wavelengths range.Raman spectroscopy can be used as a quick, lossless and unambiguous method to determine the number of graphene layers. It has also played an important role in the structural characterization of GO.更多还原