一維奈米碳材料之合成

Abstract

在本研究分為三大部分，其一為利用具等向性性質 (isotropic) 的瀝青來作為前驅物，使其在573 K軟化流入陽極處理氧化鋁 (Anodic Aluminum oxide，AAO)的孔道中，再予以升溫至973 K來碳化而可得到石墨層排列為垂直纖維長軸，且與AAO孔洞大小相似 (直徑為60–200 nm、長度為數十nm) 的奈米碳纖維，其石墨層間距約為0.39 nm。 其二為在1073 K下通入乙炔，由於氧化鋁的催化性質，會使乙炔在AAO的孔道中進行裂解環化反應，而可得到石墨層排列為平行碳管長軸且與AAO孔洞大小相似的奈米碳管，且其石墨層間距約為0.38 nm，管壁厚度為17–20 nm。 其三以鋁片為基材，其上塗佈氫化鈉或鈉金屬作為催化劑前驅物，在溫度為623 K時通入乙炔一小時來進行反應，此法能成功的得到不同型態的一維碳材，如直徑約在數μm的海膽狀長條結構或直徑為數十至數百nm的彎曲奈米碳絲線等，這些產物長度皆在數十μm且為非結晶性。

The thesis are divided into three parts. In the first part, a simple method to prepare carbon nanofibers is described. Pitch powders were placed above anodic aluminum oxide membranes (AAO) and heated in a tube furnace at 573 K to soften the pitch so that it can flow into the AAO channels. Then, the temperature was raised to 973 K for further carbonization. The diameter of the nanofibers (60–200nm) can be controlled by the pore size of AAO. The graphene layers of the carbon nanofibers were perpendicular (orthogonal) to the fiber axis. The d–spacing of the graphene layers was estimated to be 0.39 nm. In the second part, acetylene was decomposed inside the AAO channels to form carbon nanotubes at 1073 K. The CNT diameter varied with the diameter of the AAO channels. The graphene layers of carbon nanotubes were parallel to the tube axis, and the d–spacing of the graphene layers was estimated to be 0.38 nm. In the third part, aluminum foils coated with sodium or sodium hydride was served as substrates, and acetylene was used as the carbon source. The reaction was kept at 623 K for 1h to grow one-dimensional carbon structures, such as rods with diameters of several micrometers and wires with diameters of tens to hundreds nanometers. All these products were amorphous.