Instituto de Ciência e Tecnologia, Universidade Federal de São Paulo, 12231-280, São José dos Campos, SP, Brazil.
Nanoscale. 2015 Oct 28;7(40):17055-62. doi: 10.1039/c5nr04647e.
Graphene oxide (GO) holds significant promise for electronic devices and nanocomposite materials. A number of models were proposed for the GO structure, combining carboxyl, hydroxyl, carbonyl and epoxide groups at different locations. The complexity and variety of GO isomers, whose thermodynamic stability and formation kinetics depend on the applied conditions, make determination of the GO structure with atomistic precision challenging. We report high level theoretical investigation of multiple molecular configurations, which are anticipated in GO. We conclude that all oxygen containing groups at the GO surface are thermodynamically permitted, whereas the 'edge' positions are systematically more favorable than the 'center' and 'side' positions. We discuss a potentially novel type of chemical bond or bonding reinforcement in GO, which consists of a covalent bond and a strong electrostatic contribution from a polarized graphene plane. We observe and analyze significant modifications of the graphene geometry and electronic structure upon oxidation. The reported thermodynamic data guide experiments aimed at deciphering the GO chemical composition and structure, and form the basis for predicting GO properties required for nano-technological applications.
氧化石墨烯（GO）在电子器件和纳米复合材料领域具有广阔的应用前景。GO 的结构提出了许多模型，其中包括不同位置的羧基、羟基、羰基和环氧基。GO 异构体的复杂性和多样性，以及它们的热力学稳定性和形成动力学取决于应用条件，这使得原子精度确定 GO 的结构具有挑战性。我们报告了对 GO 中预期存在的多种分子构型的理论研究。我们得出的结论是，GO 表面的所有含氧基团在热力学上都是允许的，而“边缘”位置比“中心”和“侧面”位置更有利。我们讨论了 GO 中一种潜在的新型化学键或键强化类型，它由共价键和极化石墨烯平面的强静电贡献组成。我们观察并分析了氧化过程中石墨烯几何形状和电子结构的显著变化。所报道的热力学数据为旨在解析 GO 化学成分和结构的实验提供了指导，并为预测纳米技术应用所需的 GO 特性奠定了基础。
