Single sheet functionalized graphene by oxidation and thermal expansion of graphite
Single sheet functionalized graphene by oxidation and thermal expansion of graphite
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DOI：
10.1021/cm0630800
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发表时间：
2007-09-04
影响因子：
8.6
通讯作者：
Aksay, Ilhan A.
中科院分区：
文献类型：
--
作者：
McAllister, Michael J.;Li, Je-Luen;Aksay, Ilhan A.
详细分析了氧化石墨制备功能化石墨烯薄片的热膨胀机理。当氧化石墨的环氧基和羟基中心的分解速率超过放出气体的扩散速率时，就会发生剥离，从而产生超过将石墨烯片材保持在一起的范德华力的压力。将反应速度的阿累尼乌斯依赖关系与基于努森扩散计算的扩散系数进行比较，表明临界温度为550摄氏度，必须超过这个温度才能发生剥离。由于其起皱的性质，官能化和有缺陷的石墨烯薄片不会坍塌回氧化石墨，而是高度聚集。在适当的溶剂中超声分散后，原子力显微镜的统计分析表明，观察到的薄片中80%是单片的。
A detailed analysis of the thermal expansion mechanism of graphite oxide to produce functionalized graphene sheets is provided. Exfoliation takes place when the decomposition rate of the epoxy and hydroxyl sites of graphite oxide exceeds the diffusion rate of the evolved gases, thus yielding pressures that exceed the van der Waals forces holding the graphene sheets together. A comparison of the Arrhenius dependence of the reaction rate against the calculated diffusion coefficient based on Knudsen diffusion suggests a critical temperature of 550 degrees C which must be exceeded for exfoliation to occur. As a result of their wrinkled nature, the functionalized and defective graphene sheets do not collapse back to graphite oxide but are highly agglomerated. After dispersion by ultrasonication in appropriate solvents, statistical analysis by atomic force microscopy shows that 80% of the observed flakes are single sheets.