The role of electrolyte acid concentration in the electrochemical exfoliation of graphite: Mechanism and synthesis of electrochemical graphene oxide
The role of electrolyte acid concentration in the electrochemical exfoliation of graphite: Mechanism and synthesis of electrochemical graphene oxide
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DOI：
10.1016/j.nanoms.2019.07.001
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发表时间：
2019-09
影响因子：
9.9
通讯作者：
Sean E. Lowe;Ge Shi;Yubai Zhang;Jiadong Qin;Lixue Jiang;Shuaiyu Jiang;M. Al‐Mamun;Porun Liu
中科院分区：
文献类型：
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作者：
Sean E. Lowe;Ge Shi;Yubai Zhang;Jiadong Qin;Lixue Jiang;Shuaiyu Jiang;M. Al‐Mamun;Porun Liu
电化学已经成为从石墨合成石墨烯和氧化石墨烯的主要途径。阳极石墨氧化通常与稀无机酸或含水盐电解质一起使用。在该系统中，电解质酸浓度似乎是一个关键参数。然而，酸浓度的影响，特别是在低浓度下，仍然没有完全理解。为了解决这个问题，我们使用填充床电化学反应器在2-16 M硫酸中合成七种不同的电化学氧化石墨（EGO）产物。对产物进行了详细的XRD、XPS、拉曼、电导率和光学显微镜分析。我们发现稀酸（<10 M）的氧化石墨比强酸中产生的氧化石墨结晶度低，氧化程度低。石墨表面的析氧反应影响阳极的结构变化、氧化机理和电化学腐蚀。EGO电导率也受到电解质酸度的强烈影响。我们表明，良好的氧化，但合理的导电性，单层氧化石墨烯可以从7.1 M酸生产。这些结果拓宽了我们对石墨电化学的理解，并将为未来的电化学石墨烯合成工作提供信息。
Electrochemistry has emerged as a major route for graphene and graphene oxide synthesis from graphite. Anodic graphite oxidation is commonly used with dilute mineral acid or aqueous salt electrolytes. In this system, the electrolyte acid concentration appears to be a critical parameter. However, the effect of the acid concentration, particularly at low concentrations, is still not fully understood. To address this issue, we used a packed bed electrochemical reactor to synthesize seven different electrochemical graphite oxide (EGO) products in 2–16 M sulfuric acid. Detailed XRD, XPS, Raman, conductivity and optical microscopy analysis of the products was carried out. We found dilute acid (<10 M) graphite oxides were less crystalline and less oxidized than those produced in stronger acids. The oxygen evolution reaction at the graphite surface appears to affect the structural changes, oxidation mechanism, and electrochemical corrosion of the anode. EGO conductivity is also strongly affected by the electrolyte’s acidity. We show that well oxidized, yet reasonably conductive, single layer graphene oxide can be produced from 7.1 M acid. These results broaden our understanding of graphite electrochemistry and will serve to inform future electrochemical graphene synthesis efforts.