氧化程度对热剥离石墨烯电化学性能的影响

Effects of oxidation degree on the electrochemical performances of thermal exfoliation graphene

采用改进Hummers法,在不同KMnO4用量下制得了不同氧化程度的系列氧化石墨,并以其为前驱体在N2中经400℃热还原制备了石墨烯。利用XRD、FT-IR、Raman光谱与SEM表征了所得石墨烯的结构、官能团及表面形貌,通过循环伏安和恒流充放电测试研究了氧化石墨的氧化程度对石墨烯电化学性能的影响。结果表明,当KMnO4用量较低(<1.0 g)时,前驱体氧化程度较低,不能被剥离;当KMnO4用量较高(≥1.0 g)时,前驱体氧化程度增高,可实现剥离制备石墨烯。随着前驱体氧化程度增加,所制石墨烯堆叠层数与sp2平均尺寸逐渐减小,含氧官能团与缺陷逐渐增多,比容量逐渐增大。

Graphite oxide（GO） samples in different oxidation degrees were prepared by improved Hummers method with different dosages of KMnO4. Graphenes were prepared by thermal exfoliate of the obtained graphite oxide in N2 at 400 ℃. The structure, functional groups, surface morphology of the prepared graphenes were characterized by XRD, FT-IR, Raman spectroscopy and SEM. The effects of oxidation degree of the precursor on the electrochemical performances of graphene were explored by cyclic voltammetry and galvanostatic charge-discharge tests. The results show that the precursor can＇t be exfoliated for low oxidation degree when the dosage of KMnO4 is lower than 1.0 g; and the precursor can be exfoliated to realize the preparation of graphene for higher oxidation degree when the dosage of KMnO4 is no less than 1.0 g. With the increase of the oxidation degree of the precursor, the stacked layers number and the average diameter of sp2 area decrease, the content of oxygen functional groups and defect increase, while the specific capacity of the graphene samples increases.