School of Physical and Mathematical Science, Division of Chemistry and Biological Chemistry, Nanyang Technological University, 21 Nanyang Link, Singapore.
Phys Chem Chem Phys. 2012 Oct 5;14(37):12794-9. doi: 10.1039/c2cp41462g.
Electrochemical applications of graphene are of very high importance. For electrochemistry, bulk quantities of materials are needed. The most common preparation of bulk quantities of graphene materials is based on oxidation of graphite to graphite oxide and subsequent thermal exfoliation of graphite oxide to thermally reduced graphene oxide (TR-GO). It is important to investigate to which extent a reaction condition, that is, composition of the oxidation mixture and size of graphite materials, influences the properties of the resulting materials. We characterised six graphite materials with a range of particle sizes (0.05, 11, 20, 32, 35 and 41 μm) and the TR-GO products prepared from them by use of scanning electron microscopy, Raman spectroscopy and X-ray photoelectron spectroscopy. Cyclic voltammetric performance of the TR-GO samples was compared using ferro/ferricyanide and ascorbic acid. We observed no correlation between size of initial graphite and properties of the resultant TR-GO such as density of surface defects, amount of oxygen-containing groups, or rate of heterogeneous electron transfer (HET). A positive correspondence between HET rate and high defect density as well as low amounts of oxygen functionalities was noted. Our findings will have profound influence upon practical fabrication of graphene for applications in sensing and energy storage devices.
石墨烯在电化学领域有着非常重要的应用。对于电化学来说，需要大量的材料。大量石墨烯材料的最常见制备方法是基于石墨的氧化，得到氧化石墨，然后将氧化石墨热解，得到热还原氧化石墨烯（TR-GO）。研究反应条件，即氧化混合物的组成和石墨材料的尺寸，对得到的材料的性质有多大影响，这一点非常重要。我们使用扫描电子显微镜、拉曼光谱和 X 射线光电子能谱对六种具有不同粒径（0.05、11、20、32、35 和 41 μm）的石墨材料和由它们制备的 TR-GO 产物进行了表征。使用亚铁/铁氰化钾和抗坏血酸比较了 TR-GO 样品的循环伏安性能。我们没有观察到初始石墨的大小与 TR-GO 的性质之间存在相关性，如表面缺陷密度、含氧基团的数量或非均相电子转移（HET）的速率。我们注意到 HET 速率与高缺陷密度以及低氧官能团含量之间存在正相关关系。我们的研究结果将对用于传感和储能器件的石墨烯的实际应用产生深远的影响。
