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首页> 外文期刊>Journal of Materials Research >Ion transport and electrochemical tuning of Fermi level in single-wall carbon nanotubes: In situ Raman scattering
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Ion transport and electrochemical tuning of Fermi level in single-wall carbon nanotubes: In situ Raman scattering

机译：单壁碳纳米管中费米能级的离子迁移和电化学调节：原位拉曼散射

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摘要

The in situ Raman spectroscopy technique was used to investigate the ion transport and to determine the concomitant electrochemical tuning of Fermi level in single-wall carbon nanotubes. The variation of structural bonding in a single-wall carbon nanotube bundle dipped in aqueous alkaline earth halide electrolyte such as CaCl_2 with electrochemical biasing was monitored. This is because Raman scattering can detect changes in C-C bond length through radial breathing mode (RBM) at ～184 cm~(-1), which varies inversely with the nanotube diameter and the G band at ～1590 cm~(-1), varying with the axial bond length. Consistent reversible and substantial variation in Raman intensity of both modes was induced by electrode potential point at the fine and continuous tuning (alternatively, emptying/depleting or filling) of the specific bonding and anti-bonding molecular states. Qualitatively, the results were explained in terms of changes in the energy gap occurring between the one-dimensional van Hove singularities present in the electron density of states, possibly arising due to the alterations in the overlap integral of π bonds between the p orbitals of the adjacent carbon atoms. We estimated the extent of variation of the absolute potential of the Fermi level and overlap integral (γ_0) between the nearest-neighbor carbon atoms by modeling the electrochemical potential dependence of Raman intensity. Observations also suggested that the work function of the tube becomes larger for the metallic nanotubes in contrast to the simultaneously present semiconducting nanotubes.
机译：原位拉曼光谱技术用于研究离子迁移，并确定单壁碳纳米管中费米能级的伴随电化学调节。监测了单壁碳纳米管束在电化学偏压下浸入碱金属卤化物水溶液（如CaCl_2）中的结构键变化。这是因为拉曼散射可以通过〜184 cm〜（-1）处的径向呼吸模式（RBM）检测CC键长度的变化，该变化与纳米管直径和〜1590 cm〜（-1）的G带成反比，随轴向粘结长度而变化。电极电位点在特定键合和反键合分子态的精细和连续调节（或者是排空/耗尽或填充）上引起了两种模式拉曼强度的一致可逆和实质性变化。定性地，用状态电子密度中存在的一维范霍夫奇异性之间发生的能隙变化来解释结果，这可能是由于电子的p轨道之间π键的重叠积分发生了变化而引起的。相邻的碳原子。我们通过对拉曼强度的电化学电势依赖性进行建模，估计了费米能级的绝对电势的变化程度以及最近邻碳原子之间的重叠积分（γ_0）。观察结果还表明，与同时存在的半导体纳米管相比，金属纳米管的管功函数变大。

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  • 来源
    《Journal of Materials Research》 |2007年第3期|p.603-614|共12页
  • 作者

    S. Gupta;

  • 作者单位

    Department of Physics and Materials Science, Missouri State University, Springfield, Missouri 65897;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);美国《生物学医学文摘》(MEDLINE);
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 工程材料学;
  • 关键词

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