Nuclear magnetic resonance study of ion adsorption on microporous carbide-derived carbon
Nuclear magnetic resonance study of ion adsorption on microporous carbide-derived carbon
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DOI：
10.1039/c3cp51210j
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发表时间：
2013-01-01
影响因子：
3.3
通讯作者：
Grey, Clare P.
中科院分区：
文献类型：
--
作者：
Forse, Alexander C.;Griffin, John M.;Grey, Clare P.
对多孔炭中离子吸附的详细了解是设计和改进双电层电容器的关键，也就是通常所说的超级电容器。在这项工作中，核磁共振(核磁共振)谱被用来研究多孔碳化物衍生碳的离子吸附。这些以微孔为主的材料具有可调节的孔径，这使得能够系统地研究孔径对离子吸附的影响。对电解质阴离子和阳离子进行的多核核磁共振实验揭示了碳内部的两个主要环境。孔内离子(在低频率下观察到)被吸附在孔内，而外离子(在较高频率下观察到)不被吸附，而是在碳颗粒之间的大量电解液中。我们所有的实验都是在没有外加电势的情况下进行的，目的是为了评估与离子吸附相关的机理，而不是电吸附的贡献。我们的结果表明，阴离子和阳离子的吸附行为相似。此外，我们还探讨了样品取向的影响，结果表明样品取向对核磁共振谱有显著影响。最后，我们证明了C-13->；H-1交叉极化实验能够使磁化作用从碳结构转移到被吸附的物种，从而允许选择性地观察被吸附的离子并确认我们的光谱归属。
A detailed understanding of ion adsorption within porous carbon is key to the design and improvement of electric double-layer capacitors, more commonly known as supercapacitors. In this work nuclear magnetic resonance (NMR) spectroscopy is used to study ion adsorption in porous carbide-derived carbons. These predominantly microporous materials have a tuneable pore size which enables a systematic study of the effect of pore size on ion adsorption. Multinuclear NMR experiments performed on the electrolyte anions and cations reveal two main environments inside the carbon. In-pore ions (observed at low frequencies) are adsorbed inside the pores, whilst ex-pore ions (observed at higher frequencies) are not adsorbed and are in large reservoirs of electrolyte between carbon particles. All our experiments were carried out in the absence of an applied electrical potential in order to assess the mechanisms related to ion adsorption without the contribution of electrosorption. Our results indicate similar adsorption behaviour for anions and cations. Furthermore, we probe the effect of sample orientation, which is shown to have a marked effect on the NMR spectra. Finally, we show that a C-13 -> H-1 cross polarisation experiment enables magnetisation transfer from the carbon architecture to the adsorbed species, allowing selective observation of the adsorbed ions and confirming our spectral assignments.