采用改进的浮动催化化学气相沉法(FCCVD)制了直径可控的多壁碳纳米管(MWCNTs).改进的FCCVD方法关键在于甲苯以气体的形式进入反应体系避免液体甲苯在高温下瞬间气化造成CNTs直径不可控.考察了二茂铁升华温度、载气中氢气含量,载气流量等因素对MWCNTs的直径影响.结果表明:改变二茂铁的升华温度可以控制CNTs的直径分布,当二茂铁升华温度从348 K升高到378 K时,MWCNTs的直径分布从30~130 nm降到60~90 nm;氢气的存在使得CNTs的直径大幅度的减小,当氢气含量为30 vol%时,碳纳米管的直径降至为20~40 nm;提高载气流速也使得CNTs直径随着载气流量的增加而逐渐减小.
Multi-wall carbon nanotubes (MWCNTs) with controlled diameters were synthesized by an improved-floating catalyst chemical vapor deposition method, using toluene and ferrocene as a carbon source and catalyst precursor, respectively.Ferrocene was sublimed in a heater and carried as a gas mixed with toluene vapor into a reactor where MWCNTs were formed.The effects of the sublimation temperature, hydrogen content in the gas mixture and gas flow rate on the diameter and diameter distribution of the CNTs formed were investigated.Results indicated that the CNT diameter distributions could be controlled by changing the sublimation temperature.The higher the sublimation temperature, the narrower the distribution of CNT diameters.The average CNT diameter decreased and levelled off with increasing hydrogen content in the gas mixture from 0 to 40 vol%.The CNT diameter decreased with increasing gas flow rate.
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