dc.description.abstract | In this study, we use Pt and Pt-Ru catalysts for the arc discharge method to synthesize carbon nanotube (CNT), hoping that there will be Pt or Pt-Ru catalysts on the carbon nanotube. So the products can be used in the direct methanol fuel cell directly. In the experiments, we changed the operating current, catalyst loading and the composition of the catalyst. The CNTs thus produced are characterized by SEM, TEM and Raman spectroscopy. SEM results are used to characterize the CNT formation and shape. TEM results are used to observe the catalyst on the CNTs. Raman spectra are used to characterize the purity of the CNTs.
Pt is not as useful as Fe, Co, Ni in synthesizing carbon nanotube. In this work, we did not find CNTs in a few cases, especially when the synthesizing current is low. But with 150 A, we find CNTs in all cases. Also, if we use Pt-Ru instead of Pt, we can find CNTs in all cases. So Pt-Ru catalyst is more effective than Pt in catalyzing CNT formation.
Increasing the loading of the Pt or Pt-Ru does not increase the CNT yield. According to the SEM results, we find more amorphous carbons and particles as the catalyst loading is increased. In the Raman spectra, we find the D-Band intensity is also increased, and therefore the value of IG/ID decreases. So the catalyst loading should not be too high.
On the other hand, as the synthesizing current is increased, the D-Band and G-Band peaks move to lower frequencies. The micro structures of the Multiwalled carbon nanotubes may be different due to different energy inputs. Suitable operating current is very important to carbon nanotube. With low synthesizing current, there is more amorphous carbon and carbon particles. The value of IG/ID increases as the synthesizing current is increased from 80 A to 100 A, and then decreases as the synthesizing current is increased from 100 A to A. | en_US |