Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371;
Department of Inorganic Chemistry, Institute of Chemical Technology, 166 28 Prague 6, Czech Republic;
Proc Natl Acad Sci U S A. 2014 Sep 23;111(38):13774-9. doi: 10.1073/pnas.1413389111. Epub 2014 Sep 8.
The synthesis of graphene materials is typically carried out by oxidizing graphite to graphite oxide followed by a reduction process. Numerous methods exist for both the oxidation and reduction steps, which causes unpredictable contamination from metallic impurities into the final material. These impurities are known to have considerable impact on the properties of graphene materials. We synthesized several reduced graphene oxides from extremely pure graphite using several popular oxidation and reduction methods and tracked the concentrations of metallic impurities at each stage of synthesis. We show that different combinations of oxidation and reduction introduce varying types as well as amounts of metallic elements into the graphene materials, and their origin can be traced to impurities within the chemical reagents used during synthesis. These metallic impurities are able to alter the graphene materials' electrochemical properties significantly and have wide-reaching implications on the potential applications of graphene materials.
石墨烯材料的合成通常是通过将石墨氧化为氧化石墨，然后再进行还原过程来实现的。氧化和还原步骤都有很多方法，这会导致最终材料中不可预测的金属杂质污染。这些杂质已知会对石墨烯材料的性能产生重大影响。我们使用几种流行的氧化和还原方法，从极其纯净的石墨中合成了几种还原氧化石墨烯，并在合成的每个阶段跟踪金属杂质的浓度。我们表明，氧化和还原的不同组合会将不同类型和数量的金属元素引入石墨烯材料中，其来源可以追溯到合成过程中使用的化学试剂中的杂质。这些金属杂质能够显著改变石墨烯材料的电化学性质，并对石墨烯材料的潜在应用产生广泛影响。
