Diameter and metallicity dependent redox influences on the separation of single-wall carbon nanotubes
Diameter and metallicity dependent redox influences on the separation of single-wall carbon nanotubes
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DOI：
10.1021/nl051840k
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发表时间：
2005-12-01
期刊：
影响因子：
10.8
通讯作者：
Papadimitrakopoulos, F
中科院分区：
文献类型：
--
作者：
Kim, SN;Luo, ZT;Papadimitrakopoulos, F
Recently, it has become possible to separate and/or enrich fractions of single-wall carbon nanotubes (SWNTs) according to type (or otherwise termed "metallicity") and diameter (4). Exposure of acid-treated SWNTs to amines has shown such separation. In this contribution, we describe the underlying mechanism for this separation and provide a better description of the physicochemical properties of charge-stabilized SWNT dispersions in polar aprotic media, such as N,N-dimethylformide (DIVIF). With the establishment of the reversible nature of the redox chemistry, SWNTn+ + (n/2)H2O SWNT + nH(+) + (n/4)O-2, amine-induced pH changes as well as variations in H2O and O-2 concentration in DMF are shown to cause differential partial-reduction trends according to d(t) and metallicity. At a pH of 10, the (n,m)-SWNTs that resist complete reduction to their undoped state remain in suspension while the rest that lose their charges populate the precipitate. These d(t)- and metallicity-dependent redox and separation trends are modeled based on the Gibbs free energy and charge loss as it pertains to the (nm)-dependent SWNT integrated density of states (I-DOS) across the corresponding pH-induced redox jump. At a given redox potential, the relative placement of the van Hove singularities and continuum determines the amount of charge left on various (nm)-SWNTs that governs their relative dispersion stability in DMF.
