Low-temperature synthesis of amorphous carbon nanocoils via acetylene coupling on copper nanocrystal surfaces at 468 K: A reaction mechanism analysis
Low-temperature synthesis of amorphous carbon nanocoils via acetylene coupling on copper nanocrystal surfaces at 468 K: A reaction mechanism analysis
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DOI：
10.1021/jp054412b
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发表时间：
2005-11-24
影响因子：
3.3
通讯作者：
Cui, ZL
中科院分区：
文献类型：
--
作者：
Qin, Y;Jiang, X;Cui, ZL
以纳米铜为催化剂，乙炔为气源，在常压下合成了一种新型的非晶螺旋碳纳米纤维。纳米纤维生长在468 K，这是通过普通金属催化的碳氢化合物的热化学气相沉积的最低温度，并表现出双螺旋形式的对称生长模式。IR、XRD、拉曼和C/H摩尔比分析表明，该聚合物具有弱的反式聚乙炔特征。纳米纤维是固体聚合物和少量碳的混合物。根据超高真空（UHV）条件下乙炔在铜（111）、（110）和（001）面上的吸附、脱附性质和表面反应的研究结果，提出了反应机理。超高真空条件下乙炔在铜单晶表面的反应机理确实反映了常压下实际催化条件下的反应机理。纳米纤维的生长主要是通过乙炔偶联到铜表面的固体聚合物。乙炔也偶联产生少量的液体低聚物和气体产物，并在纤维生长期间经历轻微的碳沉积。
A new type of amorphous helical carbon nanofibers has been synthesized using copper nanocatalysts and an acetylene gas source at atmospheric pressure. The nanofibers are grown at 468 K, which is the lowest temperature by ordinary metal-catalyzed thermal chemical vapor deposition of hydrocarbon, and exhibit a symmetric growth mode in the form of twin helices. IR, XRD, Raman, and C/H molar ratio analyses reveal a polymer-like structure with a weak trans-polyacetylene feature. The nanofibers are a mixture of solid polymers and a small amount of carbon. A reaction mechanism has been proposed on the basis of the previous studies of acetylene adsorption, desorption properties, and surface reactions on copper (111), (110), and (001) planes under ultrahigh-vacuum (UHV) conditions as well as the results obtained in our study. The reaction mechanism of acetylene on copper single-crystal surfaces under UHV conditions indeed reflects the reaction mechanism under practical catalytic conditions at atmospheric pressure. The nanofibers grow mainly via acetylene coupling to solid polymers on copper nanocrystal surfaces. Acetylene also couples to yield small amounts of liquid oligomers and gaseous products, and undergoes slight carbon deposition during the fiber growth.