Carbon Preparation And Field Emission Properties Of Doped Carbon Nanotubes

The multi-wall carbon nanotubes (MWCNTs), aligned MWCNTs, MWCNTs catalysized by nano-gold and Indium-doped MWCNT have been synthesized by thermal decomposition of xylem. The scanning electron microscopy, transmission electron microscopy and Raman spectroscopy were used to characterize these nantoubes. The results show that MWCNTs and aligned MWCNTs have better crystalline order and typically graphitic Raman bands. Indium-doped MWCNTs have different morphology compared with pristine MWCNTs. The Indium incorporation has great effect on the degrees of curve and defect of nanotubes. Raman spectroscopy studies further confirm that Indium-doped MWCNT have worse crystallization and more defects. MWCNTs catalysized by nanogold have been produced on Si and stainless steel substrates, which revealed that nano-sized gold grains could catalyze MWCNTs' growth, and the studies of SEM and Raman spectroscopic indicated that stainless steel substrates favor the growth of MWCNTs with better crystallization.Based on the above studies, we fabricated MWCNTs cathodes on different substrates by rotated-coating method. The field emission measurements were carried out in a vacuum chamber with a 5.0 × 10~5Pa pressure and their field emission properties have also been studied. From the field emission data we draw the j-E curving line and F-N curving line, from which we calculated the averaged field-enhancing factor 6, the current degradation was also discussed. We conclude that the method of coating conductive gel on substrates can improve the field electron emission capability and emission stability. The aligned MWCNTs grown on Si substrate have better field electron emission capability. Compared with the pristine MWCNTs, the Indium-doped MWCNTs which have more defects and different morphology exhibit better field emission properties. In the case of nanogold-catalyzed MWCNTs, the fild-emission property and stability of which is better than ferrocene-catalyzed MWCNTs. We think this result maybe from the lower work function of nanogold-catalyzed MWCNTs.