空气氧化法对纳米碳管场发射性能的影响

以镍金属为催化剂,在600℃条件下,采用化学气相沉积法(CVD)制备碳纳米管。将制得的碳纳米管用高能球磨法处理0.5～1h后,以空气氧化法进行提纯,并研究了氧化温度对碳纳米管形貌和场发射性能的影响。用扫描电镜、Raman光谱分别对300～500℃的氧化提纯后的碳纳米管的形貌和结构进行了表征。结果表明:碳纳米管的场发射性能随温度的升高而升高,经400～450℃加热10min后,非晶碳成分减少,碳管纯度得到提高,场发射性能达到最高;当氧化温度继续升高时,碳纳米管的缺陷密度增大,非晶化程度增加,场发射特性变差。因此,通过控制氧化温度可以有效提高碳纳米管的纯度和场发射性能。

Effects of Air Oxidation on Field Emission Properties of Carbon Nanotubes

Multiwall carbon nanotubes (CNTs) were prepared by the catalytic decomposition of acetylene at 600 ℃ using Ni as catalysts, and then were treated by ball-milling for 0.5～1 h. The treated CNTs were purified by removing most of amorphous carbon using air oxidation method at 300～500 ℃. The morphologies and field emission properties of the oxidized CNTs were changed, mainly depending on the oxidation temperature. The field emission current density was increased to a maximum, and then decreased with increasing the oxidation tempe-rature. When the CNTs were oxidized at 400 ℃ for 10 min, the field emission current density reached to 126.5 μA/cm2 at the applied field of 4.41 V/μm. As a result, the most of amorphous carbon was removed and the purity of the CNTs was improved greatly. When the oxidized temperature is 400～450 ℃, the purified CNTs showed excellent field emission properties, such as high emission current density and uniform luminescence spots distribution.