Abstract
The Flame pyrolysis method used to synthesize carbon nanotubes was studied in this work. In order to improve the quality of synthesized carbon nanotubes, it is important to change the corresponding natures of the catalyst. Two catalyst preparation methods, namely, the sol-gel method and the impregnation method, were compared in this experiment. The properties of the catalyst are analyzed in depth by energy dispersive spectrometer (EDS), x-ray diffraction (XRD), temperature program reduction (TPR). The generation of carbon nanotubes was systematically analysed through scanning electron microscope (SEM), molecule dynamics (MD), raman spectroscopy and transmission electron microscope (TEM). The results show that the catalysts prepared by the impregnation method are stickier, dispersed and easier to dip onto the probe or substrate, which is beneficial for the large-scale production of carbon tubes. The specific surface area of alumina is larger and the iron and molybdenum oxide are more evenly dispersed on the surface of alumina. The carbon nanotubes produced by the catalysts prepared by impregnation method are flatter and have less impurities. The ratio of ID/IG+ is 29.7% lower than that of the sol-gel method in the Raman spectra. The TEM statistics show that the average diameter of the carbon tubes decreases by 23.3%. Therefore, the impregnation method can improve the quality of carbon nanotubes in the case of a similar degree of difficulty in the preparation of the catalyst.
Highlights
Since carbon nanotubes were discovered in 1991,1 because of their excellent physical properties, they have been widely studied in the fields of electronics,[2] hydrogen storage, biological probes,[3] field emission,[4] heat conduction,[5] characteristic materials and so on
Part of them fall off in steady flow, some are covered by carbon tubes, and in addition to this, there are a few catalysts in the terminal of CNTs
035111-7 Guo et al x-ray diffraction (XRD) that the catalyst prepared by the impregnation method has higher alumina content and smaller particles, it shows that the specific surface area of alumina is larger and the iron and molybdenum oxide are more evenly dispersed on the surface of alumina, and the diameter of the synthesized carbon nanotubes is reduced the result of the analysis is in agreement with the result of the observation and analysis of scanning electron microscope (SEM)
Summary
Since carbon nanotubes were discovered in 1991,1 because of their excellent physical properties, they have been widely studied in the fields of electronics,[2] hydrogen storage, biological probes,[3] field emission,[4] heat conduction,[5] characteristic materials and so on. The impregnation method was introduced to compare with the sol-gel method. The principle and procedure of the impregnating method and sol-gel method are obviously different, on the other hand, the morphology and quality of the catalysts and carbon tubes prepared by the two methods are different. In this study, using EDS, SEM, MD, XRD, TPR Raman spectroscopy and TEM, we compare the two preparation methods to explore better catalyst preparation methods for synthesising carbon nanotubes under specific conditions
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