Interactions and reactions of transition metal clusters with the interior of single-walled carbon nanotubes imaged at the atomic scale.
Interactions and reactions of transition metal clusters with the interior of single-walled carbon nanotubes imaged at the atomic scale.
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DOI：
10.1021/ja208746z
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发表时间：
2012-02
影响因子：
15
通讯作者：
T. Zoberbier;T. Chamberlain;J. Biskupek;N. Kuganathan;S. Eyhusen;E. Bichoutskaia;U. Kaiser;A. Khlobystov
中科院分区：
文献类型：
--
作者：
T. Zoberbier;T. Chamberlain;J. Biskupek;N. Kuganathan;S. Eyhusen;E. Bichoutskaia;U. Kaiser;A. Khlobystov
簇的过渡金属，W，Re，和Os，封装在单壁碳纳米管（SWNT）后表现出显着的差异，其亲和力和反应性与SWNT，所揭示的低电压像差校正的高分辨率透射电子显微镜（AC-HRTEM）。由80 keV的电子束激活，W仅与单壁碳纳米管发生微弱反应，Re在侧壁上产生局部缺陷，Os反应容易导致广泛的缺陷形成和单壁碳纳米管侧壁的收缩，然后是管状结构的总破裂。AC-HRTEM成像在原子水平上的结构转变所引起的金属-碳键的π-和σ-字符证明了什么样的关键作用，这些类型的键在控制过渡金属簇和单壁碳纳米管之间的相互作用。所观察到的反应性W < Re < Os的顺序与金属簇的尺寸、形状或取向无关，并且与金属到纳米管的结合能以及金属和SWNT之间转移的电子密度的量有关，这两者都沿着三元组W、Re、Os增加，如通过第一原理密度泛函理论计算所预测的。通过选择电子束的适当能量，可以控制（激活或排除）金属-纳米管相互作用。在低至20 keV的电子能量，没有观察到可见的转换在附近的Os-簇的纳米管。
Clusters of transition metals, W, Re, and Os, upon encapsulation within a single-walled carbon nanotube (SWNT) exhibit marked differences in their affinity and reactivity with the SWNT, as revealed by low-voltage aberration-corrected high-resolution transmission electron microscopy (AC-HRTEM). Activated by an 80 keV electron beam, W reacts only weakly with the SWNT, Re creates localized defects on the sidewall, and Os reacts readily causing extensive defect formation and constriction of the SWNT sidewall followed by total rupture of the tubular structure. AC-HRTEM imaging at the atomic level of structural transformations caused by metal-carbon bonding of π- and σ-character demonstrates what a crucial role these types of bonds have in governing the interactions between the transition metal clusters and the SWNT. The observed order of reactivity W < Re < Os is independent of the metal cluster size, shape, or orientation, and is related to the metal to nanotube bonding energy and the amount of electronic density transferred between metal and SWNT, both of which increase along the triad W, Re, Os, as predicted by first-principles density functional theory calculations. By selecting the appropriate energy of the electron beam, the metal-nanotube interactions can be controlled (activated or precluded). At an electron energy as low as 20 keV, no visible transformations in the nanotube in the vicinity of Os-clusters are observed.