Temperature and pressure dependence of molecular adsorption on single wall carbon nanotubes and the existence of an “adsorption/desorption pressure gap”
Temperature and pressure dependence of molecular adsorption on single wall carbon nanotubes and the existence of an “adsorption/desorption pressure gap”
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DOI：
10.1016/j.carbon.2009.11.018
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发表时间：
2010-06
期刊：
影响因子：
10.9
通讯作者：
Dmitry V. Kazachkin;Y. Nishimura;S. Irle;Xue Feng;R. Vidic;E. Borguet
中科院分区：
文献类型：
--
作者：
Dmitry V. Kazachkin;Y. Nishimura;S. Irle;Xue Feng;R. Vidic;E. Borguet
用程序升温脱附-质谱仪(TPD-MS)研究了丙酮与单壁碳纳米管(SWCNTs)的相互作用，考察了丙酮回流、超声或室温暴露于7.6Torr水蒸气后的相互作用。丙酮分子在∼400-900K脱附的单壁碳纳米管上吸附较强，其脱附能为100-225kJ/∼，为完整分子。在连续给药的氢化和氢化丙酮分子中，观察到完整的吸附分子与气相物种的交换。这里报道的脱附能与先前报道的碳纳米管与丙酮在高真空低温下相互作用的脱附能(∼75kJ/mol)形成鲜明对比。这一结果表明，乙醇、甲烷、正丁烷和1，3-丁二烯在碳纳米管和炭黑上的吸附也是活化吸附/脱附。量子化学计算表明，大直径单壁碳纳米管束在间隙通道中的吸附是可能的，并解释了相邻单壁碳纳米管之间强烈的弥散相互作用导致的高脱附势垒。
The interaction of acetone with single wall carbon nanotubes (SWCNTs) was studied by temperature programmed desorption with mass spectrometry (TPD-MS), after reflux, sonication, or exposure to 7.6Torr of acetone vapors at room temperature. Acetone molecules adsorb strongly on SWCNTs desorbing at ∼400–900K, corresponding to desorption energies of ∼100–225kJ/mol, as intact molecules. Exchange of intact adsorbed molecules with gas phase species was observed in successive dosing of hydrogenated and deuterated acetone molecules. The desorption energies reported here are in stark contrast to the desorption energies (∼75kJ/mol) reported earlier for SWCNTs interacting with acetone under high vacuum at cryogenic temperatures. This result suggests activated adsorption/desorption, and is also observed for adsorption of ethanol, methane, n-butane and 1,3-butadiene on SWCNTs and on carbon black. Quantum chemical calculations suggest that adsorption in interstitial channels of bundles formed of large-diameter SWCNTs is possible and can account for high desorption barriers, a result of strong dispersion interactions between neighboring SWCNTs.