Effect Of Phosphorus On The Synthesis Of Single/Multi-Walled Carbon Nanotubes

Since the discovery of multi-walled carbon nanotubes (MWNTs) in 1991 and single-walled carbon nanotubes (SWNTs) in 1993, carbon nanotubes have been one of the highlights in nanomaterial area because of their unique structural, physical and chemical properties and hence remarkable potential as a new material in a wide range of applications. It can be conjectured that with the perception and application of carbon nanotubes deepening, it will probably have great impact on human being's future. Therefore, carbon nanotubes are regarded as one of the greatest discoveries at the end of twentieth century. The mass synthesis of carbon nanotubes, especially SWNTs, is one of the severe problems in carbon nanotubes' research, and has been being a choke point in research and application of carbon nanotubes. Stability of SWNTs is another important problem in the area of carbon nanotubes.The synthesis of SWNTs by floating catalyst method, using phosphorus as promoter, was investigated in this paper. It was found that the addition of phosphorus promoter could greatly promote the yield of SWNTs. The morphology, structure of SWNTs was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Raman spectroscopy. It was concluded from the characterization that the Yarmulke cap model was operative in the growth of SWNTs, and phosphorus could enhance effectively the catalysis of iron nanopaticle, nucleation of Yarmulke cap and promote the growth of relatively smaller-diametered SWNTs. The stability of as-grown SWNTs under infrared was studied and found not stable. Structure reconstruction happened and SWNTs turned into disordered carbonaceous material.The effect of phosphorus on the purity and morphology of MWNTs by chemical vapor deposition method was investigated. It was found that the addition of phosphorus enhanced the catalysis of Fe and promoted the purity of carbon nanotubes. It was also found that the addition of phosphorus had a great effect on the morphology of carbon nanotubes. Chain-shaped carbon nanotubes, Fe nanowires-filled carbon nanotubes and bamboo-shaped carbon nanotubes were obtained and the graphitization of carbon nanotubes was enhanced.The experimental results show that phosphorus has great applicable potential in the synthesis of carbon nanotubes.