以新穎的方法合成奈米碳管及奈米氮化碳管

Abstract

利用氫化鈉熱裂解後的鈉金屬與六氯環戊二烯在623 K下反應，得到一些多樣化形態的奈米碳材料，包括海膽狀的碳球、具有方形空心的碳球及類似碳管的奈米結構。我們將具有方形空心的碳球及類似碳管之奈米結構形成歸因於反應副產物-氯化鈉的作用。樣品多樣化的形態可能是由於兩個反應物的不均勻接觸的結果。另外，我們發展了一個新的方法使氫化鈉在陽極處理氧化鋁上熱裂解，鈉金屬形成並流入陽極處理氧化鋁的孔道，在孔道上形成一層鈉膜，使陽極處理氧化鋁成為一具有反應性的模版，可與碳鹵化合物反應形成碳管。首先，我們利用六氯環戊二烯為前驅物與此模版在623 K下反應可在陽極處理氧化鋁之孔道內形成奈米碳管。經由48％氫氟酸去除陽極處理氧化鋁後，可得到排列整齊的奈米碳管陣列，其直徑為300 nm，長度為60 μm，壁厚為20 nm。若將反應溫度降到423 K，可產生管壁具有多孔洞的奈米碳管。孔洞性奈米碳管管壁上的中孔洞孔徑大小分佈可利用BJH（Barret-Joyner-Halenda）法從氮氣等溫脫附曲線計算得到，其孔洞大小十分均勻，大約落在4 nm。此外，由五氯吡啶與具反應的模版在623 K下反應，可得到高含氮量（∼17％）的奈米氮化碳管。這些奈米氮化碳管的半徑為300 nm，長度為60 μm，壁厚為20 nm，屬非結晶性材料。

The reaction between hexachlorocyclopentadiene (C5Cl6) and Na, which have been achieved by decomposing NaH thermally, can afford diversified morphologies of nano-sized carbon at 623 K, including urchin-like spheres, hollow spheres with cubic core as well as tubulate structures. The formation of cubic-cored hollow spheres and tubulate structure might be caused by NaCl by-product. The formation of diversified morphologies may be attributed to heterogeneous contact of the two reactants. Besides, we successfully developed a new strategy for formation of an reactive template by thermally decomposing NaH on AAO, which can react with carbonhalides to produce carbon tubes. First of all, reacting the reactive template with C5Cl6 at 623 K generates carbon nanotubes inside the template channels. Well-ordered carbon nanotube bundles ( diameter of 300 nm, length of 60 μm, wall thickness of 20 nm ) were isolated after the template was removed by 48％ HF. Lowering the reaction temperate to 473 K led to the formation of carbon nanotubes with porous wall. The pore size distribution data, caculated from nitrogen desorption branch of isotherms by BJH ( Barret-Joyner-Halenda ) method, showed that the mesoporous walls were uniform with narrow pore size distribution centered at 4 nm. Moreover, well-ordered CNx nanotubes with a high content of nitrogen ( x ∼17％ ) were carried out by reacting pentachloropyridine ( C5NCl5 ) with the reactive template at 623 K. The diameter of the CNx nanotubes was 300 nm, the length was 60μm, and the wall thickness was 20 nm.