Simultaneous Quantification of Electron Transfer by Carbon Matrices and Functional Groups in Pyrogenic Carbon.
Simultaneous Quantification of Electron Transfer by Carbon Matrices and Functional Groups in Pyrogenic Carbon.
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DOI：
10.1021/acs.est.8b02340
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发表时间：
2018-07
影响因子：
11.4
通讯作者：
Tianran Sun;B. Levin;Michael P. Schmidt;Juan J. L. Guzman;A. Enders;C. Martínez;D. Muller;L. T. Ang
中科院分区：
文献类型：
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作者：
Tianran Sun;B. Levin;Michael P. Schmidt;Juan J. L. Guzman;A. Enders;C. Martínez;D. Muller;L. T. Ang
热解碳含有氧化还原活性官能团和聚芳碳基质，两者都能够转移电子。已经探索了几种技术来单独表征官能团或碳基质的单独电子转移过程。然而，同时分析这两个过程仍然具有挑战性。使用的方法，采用四电极配置和双界面电子转移检测，我们区分的电子转移的官能团从电子转移的碳矩阵，同时量化它们的相对贡献的总电子转移到和从热解碳。结果表明，在低至中高温（400-500 °C）下，官能团的氧化还原循环是主要机制，对总电子转移的贡献率为100-78%;而在高温（650-800 °C）下，碳基质的直接电子转移占主导地位电子转移，贡献率为87- 100%。热解碳的光谱和衍射分析支持的电化学测量，显示从富集的官能团的分子水平的结构转变，以富集在纳米级的石墨烯域随着热解温度的增加。本研究中描述的方法提供了一种新的分析方法，可以分别量化天然热解碳中不同电子转移途径的相对重要性，并具有工程碳材料（如氧化石墨烯）的潜在应用。
Pyrogenic carbon contains redox-active functional groups and polyaromatic carbon matrices that are both capable of transferring electrons. Several techniques have been explored to characterize the individual electron transfer process of either functional groups or carbon matrices individually. However, simultaneous analysis of both processes remains challenging. Using an approach that employs a four-electrode configuration and dual-interface electron transfer detection, we distinguished the electron transfer by functional groups from the electron transfer by carbon matrices and simultaneously quantified their relative contribution to the total electron transfer to and from pyrogenic carbon. Results show that at low to intermediate pyrolysis temperatures (400-500 °C), redox cycling of functional groups is the major mechanism with a contribution of 100-78% to the total electron transfer; whereas at high temperatures (650-800 °C), direct electron transfer of carbon matrices dominates electron transfer with a contribution of 87-100%. Spectroscopic and diffraction analyses of pyrogenic carbon support the electrochemical measurements by showing a molecular-level structural transition from an enrichment in functional groups to an enrichment in nanosized graphene domains with increasing pyrolysis temperatures. The method described in this study provides a new analytical approach to separately quantify the relative importance of different electron transfer pathways in natural pyrogenic carbon and has potential applications for engineered carbon materials such as graphene oxides.