Preparation of vertically aligned carbon nanotubes by pyrolysis of phthalocyanine at lower pressure

Large scale vertically aligned carbon nanotubes (ACNTs) with a uniform length and diameter were prepared by the pyrolysis of iron(II) phthalocyanine at a low pressure. The pyrolysis was performed in a dual furnace fitted with independent temperature controller. The morphology and microstructure of ACNTs were analyzed by SEM, FESEM and TEM. The ACNTs have a cylindrical and bamboo-like structure and are multi-walled carbon nanotubus. The influences of parameters such as gas pressure, growth temperature, gas flow rate and the volume ratio of Ar to H₂ were studied. We found that ACNTs with best quality could been prepared at a pressure of 5 × 10⁴ Pa and a higher temperature above 950°C. Some properties, such as field emission, capacitor, and sensor electrode of ACNTs were studied and discussed. The results showed a very powerful ability of electron emission with a lower turn-on voltage of 0.67 V·μm^-1 (I = 1 μA), a significant performance of power capacitor and electrical conductivity, which indicated that ACNTs are new highly efficient materials for practical devices application.