Determination of the Local Chemical Structure of Graphene Oxide and Reduced Graphene Oxide
Determination of the Local Chemical Structure of Graphene Oxide and Reduced Graphene Oxide
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DOI：
10.1002/adma.201000732
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发表时间：
2010-10-25
影响因子：
29.4
通讯作者：
Zettl, Alex
中科院分区：
文献类型：
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作者：
Erickson, Kris;Erni, Rolf;Zettl, Alex
尽管石墨烯独特的电子和机械性质显示了许多有趣的应用，但所需的大规模直接合成和基于溶液的处理已被证明是困难的。[1，2]有人建议，一种官能化形式的石墨烯，氧化石墨烯(GO)，可以提供一种对溶液友好的简单、高通量的石墨烯操作方法。[2]然而，要使这种路线可行，GO必须表面上通过化学还原和热退火转化为石墨烯。不幸的是，输运测量表明，还原并退火的氧化石墨烯(RAGO)的电导率比石墨烯的低几个数量级。[2，3]这提出了一个问题：氧化的石墨烯能否有效地转化为石墨烯，如果不能，它可以转化为什么？这个问题的核心是GO和RAGO的详细原子结构，尽管它们很重要，但基本上仍然未知。[4]我们在这里展示了超高分辨率的电子显微镜图像和动力学研究，悬浮石墨烯，GO，和RAGO，使用像差校正仪器获得。应当注意的是，标签GO和RAGO(也称为化学转化的石墨烯)[5]都指的是各种各样的材料，每种材料的性能在很大程度上取决于所采用的特定合成路线。本研究为GO和RAGO提供了一种特殊的合成方法。在合成GO和RAGO的各种方法中，我们遵循了报道的最终电导率最高的方法，因为这种材料最适合作为潜在的石墨烯替代品。[2，6-11]揭示了GO和RAGO的局部和全局结构和稳定性。我们发现，正在研究的RAGO材料在结构上与石墨烯有很大的不同，在显著的电子束下是不稳定的
Although the unique electronic and mechanical properties of graphene suggest numerous intriguing applications, the requisite large-scale direct synthesis and solution-based handling have proven difficult.[1, 2] It has been suggested that a functionalized form of graphene, graphene oxide (GO), could provide a solution-friendly route to facile, high-throughput graphene manipulation.[2] For such a route to be viable, however, GO must be convertible back to graphene, ostensibly via chemical reduction and thermal annealing. Unfortunately, transport measurements indicate that the reconstituted material, reduced and annealed graphene oxide (raGO), has electrical conductivity orders of magnitude lower than that of graphene.[2, 3] This raises the question: can oxidized graphene be effectively converted back to graphene, and if not, what can it be converted to?Central to this question are the detailed atomic structures of GO and raGO, which, despite their importance, remain largely unknown.[4] We present here ultra-high-resolution transmission electron microscopy (TEM) images and dynamics studies of suspended sheets of graphene, GO, and raGO, obtained using aberration-corrected instrumentation. It should be noted that both the label GO and raGO (also referred to as “chemically converted graphene”)[5] refer to a wide variety of materials with the properties of each material being largely dependent upon the particular synthetic route employed. This study presents one particular synthetic method for GO and raGO. Among the various methods possible for synthesizing GO and raGO, we followed methods which have yielded the highest reported final conductivities, as this material would be most suitable as a potential graphene alternative.[2, 6–11] The local and global structure and stability of GO and raGO are revealed. We find that the raGO material under study is greatly structurally dissimilar to graphene, being unstable under significant electron beam