Experimentally Determined Redox Potentials of Individual (n,m) Single-Walled Carbon Nanotubes
Experimentally Determined Redox Potentials of Individual (n,m) Single-Walled Carbon Nanotubes
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DOI：
10.1002/anie.200902468
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发表时间：
2009-01-01
影响因子：
16.6
通讯作者：
Nakashima, Naotoshi
中科院分区：
文献类型：
--
作者：
Tanaka, Yasuhiko;Hirana, Yasuhiko;Nakashima, Naotoshi
自从发现碳纳米管 (CNT) 以来，许多研究小组一直致力于了解 CNT 的基本特性。单壁碳纳米管（SWNT）的氧化还原性质（即电子密度、费米能级、氧化还原电位）与具有特定直径和手性角的单壁碳纳米管结构有关，且与一对整数（n，m）唯一相关； [1, 2] 人们已经尝试使用扫描隧道光谱、[3] 氧化还原滴定法、[4] 光致发光 (PL) 测量、[5–7] 和光谱电化学来确定单壁碳纳米管的电子特性；[8–13] 然而，已经报道的氧化还原特性测定的成功率很低。最近，Paolucci 等人[12]采用可见光-近红外吸收光谱电化学来估计溶解在超干二甲基亚砜（DMSO）溶液中的单壁碳纳米管的氧化还原电位；然而，使用这种方法确定孤立的（n，m）SWNT的氧化还原电位并不容易，因为具有几种不同手性指数的SWNT在近红外区域具有彼此重叠的带隙。我们现在描述了一种简单的方法，用于在水性介质中使用近红外PL光谱电化学测定许多（在本研究中为15个）单个（n，m）SWNT的氧化还原电位。溶解CNT的策略方法对于CNT的许多应用至关重要[14]，并且包括羧甲基纤维素钠盐（CMC，支持信息中的图S1a）[15]在内的许多分散剂已被用于单独溶解SWNT。在本研究中，我们制造了一种非荧光透明氧化铟锡 (ITO) 电极，该电极采用 CMC/聚（二烯丙基二甲基氯化铵）（PDDA；支持信息中的图 S1b）流延膜进行修饰，其中包含孤立的 SWNT（有关详细信息，请参阅支持信息中的实验部分）。
Ever since the discovery of carbon nanotubes (CNTs), many groups have endeavored to understand the fundamental properties of the CNTs. The redox properties (ie electronic densities, the Fermi levels, redox potentials) of single-walled carbon nanotubes (SWNTs) are related to the structures of SWNTs that have a specified diameter and chirality angle uniquely related to a pair of integers (n, m); the so-called chiral indices.[1, 2] Many attempts have been made to determine the electronic properties of SWNTs using scanning tunneling spectroscopy,[3] redox titrimetry,[4] photoluminescence (PL) measurements,[5–7] and spectroelectrochemistry;[8–13] however, the success in the determination of the redox properties as already reported has been low. Recently, Paolucci et al.[12] employed Vis–near-IR absorption spectroelectrochemistry to estimate the redox potentials of the SWNTs dissolved in an ultradry dimethylsulfoxide (DMSO) solution; however, it is not easy to determine the redox potentials of isolated (n, m) SWNTs using this method because SWNTs with several different chiral indices have band gaps in the near-IR region that overlap one another. We now describe a simple method for the determination of the redox potentials of many (in this study, fifteen) individual (n, m) SWNTs using near-IR PL spectroelectrochemistry in an aqueous medium.Strategic approaches toward the solubilization of CNTs are essential for many applications of CNTs [14] and numerous dispersants including carboxymethylcellulose sodium salt (CMC, FigureS1a in the Supporting Information)[15] have been used to individually dissolve SWNTs. In this study, we fabricated a non-fluorescent transparent indium tin oxide (ITO) electrode modified with a cast film of CMC/poly-(diallyldimethylammonium chloride)(PDDA; Figure S1b in the Supporting Information) that contained isolated SWNTs (for details, see Experimental Section in the Supporting Information).