Selective removal of metallic single-walled carbon nanotubes with small diameters by using nitric and sulfuric acids.
Selective removal of metallic single-walled carbon nanotubes with small diameters by using nitric and sulfuric acids.
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DOI：
10.1021/jp053245c
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发表时间：
2005-09
期刊：
影响因子：
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通讯作者：
Cheol-Min Yang;Jin Sung Park;K. An;S. Lim;Kwanyong Seo;Bongsoo Kim;Kyung Ah Park;Seungwu Han
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文献类型：
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作者：
Cheol-Min Yang;Jin Sung Park;K. An;S. Lim;Kwanyong Seo;Bongsoo Kim;Kyung Ah Park;Seungwu Han
金属碳纳米管和半导体碳纳米管的共存往往是许多应用和基础研究的瓶颈。将单壁碳纳米管 (SWCNT) 溶解在 HNO3/H2SO4 混合物中，以确认金属 (m) 和半导体 (s) SWCNT 之间的不同反应性。经过HNO3/H2SO4处理，s-SWCNT保持完整，而对于直径小于1.1 nm的小SWCNT，m-SWCNT被完全去除，这通过共振拉曼和光学吸收光谱得到证实。我们还表明，溶解在 HNO3/H2SO4 溶液中的硝离子 (NO2+) 可以更好地攻击 m-SWCNT，这得到了我们的理论计算的支持。这种明显的选择性可以通过 m-SWCNT 上的带正电荷的 NO2+ 优先吸附来解释，这是由于 m-SWCNT 中费米能级上的可用电子密度更大。我们首次报道了使用 HNO3/H2SO4 溶液选择性去除小直径 m-SWCNT，这与之前报道的通过氧化蚀刻直径选择性去除 SWCNT 形成了鲜明的对比。
Coexistence of metallic and semiconducting carbon nanotubes has often been a bottleneck in many applications and much fundamental research. Single-walled carbon nanotubes (SWCNTs) were dissolved in HNO3/H2SO4 mixture to confirm differing reactivity between metallic (m) and semiconducting (s) SWCNTs. With HNO3/H2SO4 treatment, s-SWCNTs remained intact, while m-SWCNTs were completely removed for SWCNTs with small diameters less than 1.1 nm, which was confirmed by resonant Raman and optical absorption spectra. We also showed that nitronium ions (NO2+) dissolved in the HNO3/H2SO4 solution could preferably attack the m-SWCNTs, which was supported by our theoretical calculation. This clear selectivity can be explained by the preferential adsorption of positively charged NO2+ on m-SWCNTs due to more available electron densities at the Fermi level in the m-SWCNTs. We report for the first time a selective removal of small-diameter m-SWCNTs by using HNO3/H2SO4 solution, which presented a striking contrast to the diameter-selective removal of SWCNTs by oxidative etching reported previously.