Origin of the Surfactant-Dependent Redox Chemistry of Single-Wall Carbon Nanotubes
Origin of the Surfactant-Dependent Redox Chemistry of Single-Wall Carbon Nanotubes
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DOI：
10.1002/cnma.201600190
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发表时间：
2016-09-01
期刊：
影响因子：
3.8
通讯作者：
Kataura, Hiromichi
中科院分区：
文献类型：
--
作者：
Hirano, Atsushi;Kameda, Tomoshi;Kataura, Hiromichi
在十二烷基硫酸钠 (SDS) 及其类似表面活性剂（即 1-十一烷磺酸钠 (SUS) 和十二烷基苯磺酸钠 (SDBS)）存在下，通过光学吸收光谱测量来检查单壁碳纳米管 (SWCNT) 的氧化还原化学。在 SDS 和 SUS 溶液中观察到 SWCNT 的氧化还原反应，而在 SDBS 溶液中此类反应受到抑制。进行分子动力学模拟以研究表面活性剂在单壁碳纳米管周围的组装。 SDS 和 SUS 主要在 SWCNT 和某些暴露于溶剂的区域上形成单层，而 SDBS 可以预见地密集地涂覆在 SWCNT 上。结果表明，SWCNT 表面上的 SDBS 层可防止电荷转移反应；相比之下，SDS 和 SUS 的稀疏层允许通过电荷转移反应进行氧化还原化学反应。有趣的是，带正电的单壁碳纳米管作为氧化单壁碳纳米管的模型显示，由于静电相互作用，SDS和SUS溶液中单壁碳纳米管周围的表面活性剂分子数量增加，这与单壁碳纳米管胶体稳定性的手性依赖性有关。
The redox chemistry of single-walled carbon nanotubes (SWCNTs) was examined by using optical absorption spectroscopy measurements in the presence of sodium dodecyl sulfate (SDS) and its analog surfactants, that is, sodium 1-undecanesulfonate (SUS) and sodium dodecylbenzenesulfonate (SDBS). Redox reactions of the SWCNTs were observed in the SDS and SUS solutions, whereas such reactions were suppressed in the SDBS solution. Molecular dynamics simulations were performed to investigate the assembly of the surfactants around an SWCNT. SDS and SUS were shown to primarily form single layers on the SWCNT and certain solvent-exposed areas, whereas SDBS predictably densely coated the SWCNTs. The results suggest that the SDBS layer on the SWCNT surfaces prevents charge-transfer reactions; in contrast, the sparse layers of SDS and SUS allow the redox chemistry through the charge-transfer reactions. Interestingly, a positively charged SWCNT as a model for the oxidized SWCNT showed an increase in the number of surfactant molecules around the SWCNT in the SDS and SUS solutions owing to electrostatic interaction, which is related to the chirality-dependence of the SWCNT colloidal stability.