Co/MgO固体催化剂CVD法合成单壁纳米碳管的研究

CVD synthesis of single-walled carbon nanotubes by Co/MgO solid catalysts

分别用浸渍法、离子吸附沉淀法、溶胶-凝胶法制备了四组Co/MgO催化剂.1000℃时,这些催化剂均能在CH4气氛下合成单壁纳米碳管,产量受催化剂活性组分尺寸影响明显.经透射电子显微镜(TEM)和热重分析(TGA)结果发现,浸渍法中以乙醇作为溶剂制备的催化剂所制得的产物中含有最多的单壁纳米碳管;离子吸附沉淀法所得的催化剂因沉淀的活性组分颗粒过大而不适合于单壁纳米碳管的生长;溶胶-凝胶法通过优化工艺将有望获得高产率的制备单壁碳管的催化剂.TEM和电子衍射观测同时表明所制得的单壁纳米碳管的直径都分布在1nm左右,且大部分聚集成束.

Four Co/MgO catalysts for growing single-walled carbon nanotubes (SWNTs) were prepared by impregnation, ion-absorption precipitation, and sol-gel methods respectively. All the four catalysts could be used to synthesize SWNTs at 1000°C when using CH4 as carbon source; the yield was remarkably affected by the size of activation-sites of the catalysts. Transmission electron microscopy (TEM) observation and thermogravimetric analysis (TGA) showed that when ethanol was used as solvent in the impregnation method, the catalyst achieved the highest yield; and that ion-absorption precipitation was not a promising method for catalyzing SWNTs preparation due to the large scale of the activation-sites obtained by deposition. Experimental results also implied that the sol-gel method would be a hopeful technique for catalyst preparation after optimizing its process. All those SWNTs' diameters were about 1 nm and most were in big bundles as revealed by the TEM observation and the diffraction.