Role of anions on electrochemical exfoliation of graphite into graphene in aqueous acids
Role of anions on electrochemical exfoliation of graphite into graphene in aqueous acids
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DOI：
10.1016/j.carbon.2020.06.044
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发表时间：
2020-10-15
期刊：
影响因子：
10.9
通讯作者：
Lee, Seung Woo
中科院分区：
文献类型：
--
作者：
Lee, Hoyoung;Choi, Ji Il;Lee, Seung Woo
石墨阳极电化学剥离法是一种快速、低成本制备中等质量石墨烯的方法。含硫酸盐的水溶液已被确定为用于石墨到石墨烯的阴离子剥离过程的最有效的电解质条件。然而，含硫酸盐电解质的高剥离效率的起源仍然没有答案。在这项研究中，我们研究了阴离子在阳极剥离石墨通过比较不同的稀酸体系（硫酸，硝酸，磷酸和盐酸）的作用。使用原位质谱仪，循环伏安法和密度泛函理论计算建模的组合，我们发现，只有硫酸根阴离子允许可逆的嵌入行为循环伏安循环后，可能是由于最高的排斥结合能之间的石墨烯片相比，其他阴离子。因此，硫酸根阴离子容易进入石墨层促进了水分子在阳极过程期间扩散到石墨的本体中，并且随后的水氧化使得石墨能够有效地剥离成石墨烯。这些结果突出了理解电解质离子和石墨之间的相互作用对于石墨烯的电化学制造的重要性。(C)2020爱思唯尔有限公司版权所有。
Anodic electrochemical exfoliation of graphite is one of the promising methods for the fast production of graphene with moderate quality at low cost. Sulfate-containing aqueous solutions have been identified as the most efficient electrolyte condition for anionic exfoliation process of graphite into graphene. However, the origin of the high exfoliation efficiency of sulfate-containing electrolytes remains unanswered. In this study, we study the role of anions in anodic exfoliation of graphite by comparing different dilute acid systems (sulfuric, nitric, phosphoric, and hydrochloric acids). Using the combination of in-situ mass spectrometer, cyclic voltammetry, and density functional theory computation modeling, we reveal that only the sulfate anions allows reversible intercalation behavior upon cycling voltammetry cycles, probably due to the highest repulsive binding energy between graphene sheets compared to those of other anions. Therefore, the easy access of sulfate anion into the graphite layer facilitates the diffusion of water molecules into the bulk of the graphite during the anodic process, and the subsequent water oxidation enables efficient exfoliation of graphite into graphene. These results highlight the importance of understanding the interactions between electrolyte ion and graphite for the electrochemical manufacturing of graphene. (C) 2020 Elsevier Ltd. All rights reserved.