铬酸及硝酸混合液处理以增强碳纳米管场发射

为了修饰碳纳米管(CNTs)的表面型态及改变碳纳米管的表面结构, 进一步增强碳纳米管的场发射特性, 使用铬酸及硝酸的混合溶液对碳纳米管进行后处理. 采用SEM、TEM、Raman 和EDS测试手段对样品的形貌、表面成份组成和微观结构特征进行了表征. 场发射(FE)的数据显示, 经过铬酸及硝酸的混合溶液处理20 min的碳纳米管场发射电流比未经任何处理的碳纳米管场发射电流明显增加一个数量级以上, 场发射电流增强的主要原因为样品上的碳纳米管的表面型态的改变, 造成碳纳米管场发射增强因子茁的增大. 与单独使用硝酸溶液后处理比较, 使用铬酸及硝酸的混合溶液对碳纳米管进行后处理可以得到较高的场发射电流及较低的起始电场. 铬酸及硝酸的混合溶液处理方法能经济且有效增强碳纳米管的场发射特性.

Enhancement of Field Emission Characteristics for Multi-Walled Carbon Nanotubes Treated with a Mixed Solution of Chromic Trioxide and Nitric Acid

A simple acid treatment method was apphed to functionalize the surface and to modify the structures of multi-walled carbon nanotubes(CNTs)grown on silicon substrates using a mixed solution of chromic trioxide(CrO3)and nitric acid(HNO3).Scanning electron microscopy(SEM),transmission electron microscopy(TEM),Raman spectroscopy,and energy dispersive spectrometer(EDS)were employed to investigate the mechanism causing the modified field emission(FE)properties of the CNT films.After 20 min of CrO3+HNO3 treatment,the emitted currents were erdaanted by more than one order of magnitude compared with those of the untreated CNTs.This large increases in emitted current can be attributed to the favorable surface morphologies,open-ended structures,and highly curved CNT surfaces in the CNT films.These factors altogether caused an increase in the field enhancement factors of CNTs.We also demonstrated that using a mixed solution of CrO3+HNO3 post-treatment exhibited a higher emission current and a lower turn-on electric field than in the CNTs treated with HNO3.The method provides a sunple,economical,and effective way to enhance the CNT field emission properties.