Sulfur Species in Graphene Oxide
Sulfur Species in Graphene Oxide
复制标题
DOI：
10.1002/chem.201300387
复制
发表时间：
2013-07-15
影响因子：
4.3
通讯作者：
Hirsch, Andreas
中科院分区：
文献类型：
--
作者：
Eigler, Siegfried;Dotzer, Christoph;Hirsch, Andreas
氧化石墨烯(GO)的结构对其化学功能化具有至关重要的作用。然而，到目前为止，只有少数几位作者对悍马方法制备的GO中的硫含量进行了讨论。据报道，硫物种发生了水解，氧化石墨中存在稳定的磺酸基。在这份手稿中，与早先的报告不同，发现了共价结合的硫酸盐物种，这些物种在广泛的水中工作后仍然存在。此外，我们排除了GO中存在的磺酸基团作为水处理后的主要物种的可能性。我们的结果是基于热重法对氧化石墨烯的整体表征，以及随后使用质谱仪和红外光谱对分解产物的分析。到目前为止，200到300摄氏度之间的燃烧温度几乎没有得到解决。在温度依赖实验中，我们揭示了两个主要的分解步骤，这两个步骤的温度不同，并且与GO中的硫物种密切相关。在200至300摄氏度之间的分解与有机硫酸盐的降解有关，而在700至800摄氏度之间的分解与无机硫酸盐的热解有关。此外，有机硫酸盐在一定程度上与GO的反应活性有关。因此，通过在环氧基和羟基之外添加有机硫酸盐来扩展GO的结构模型，这些基团主要是共价键合在碳骨架的上方和下方。此外，环氧基团下的有机硫酸盐基团的识别使新的分子结构成为可能，并可用于解释GO在各种应用中的性质。
The structure of graphene oxide (GO) is of crucial importance for its chemical functionalization. However, the sulfur content present in GO prepared by Hummers' method has only been addressed by a few authors so far. It has been reported that hydrolysis of sulfur species takes place and that stable sulfonic groups are present in graphite oxide. In this manuscript, in contrast to earlier reports, sulfate species are identified that are covalently bound to GO and still present after extensive aqueous work-up. Additionally, we exclude the possibility that sulfonic groups are present in GO as major species after aqueous work up. Our results are based on bulk characterization of graphene oxide by thermogravimetry and subsequent analysis of the decomposition products using mass spectroscopy and infrared spectroscopy. Up to now, the combustion temperature between 200 and 300 degrees C remained almost unaddressed. In a temperature dependant experiment we reveal two main decomposition steps that differ in temperature and that are closely related to the sulfur species in GO. While the decomposition, between 200 and 300 degrees C, is related to the degradation of organosulfate, the other one, between 700 and 800 degrees C, is assigned to the pyrolysis of inorganic sulfate. Furthermore, organosulfate is to some extent responsible for the reactivity of GO. Therefore, the structural model of GO was extended by adding organosulfate in addition to epoxy and hydroxyl groups, which are predominantly covalently bound above and below the carbon skeleton. Furthermore, the identification of organosulfate groups beneath epoxy groups makes new molecular architectures feasible and can be used to explain the properties of GO in various applications.