Growth Of Single-walled Carbon Nanotubes By Composite Oxides

Single-walled carbon nanotubes have attracted extensive attention due to their excellent electrical,optical,and mechanical properties,especially in the field of electronic science.To realize their cutting-edge applications,it is necessary to prepare single-walled carbon nanotubes with narrow chiral distribution.Nowadays,various separation techniques for single-walled carbon nanotubes have been developed,such as sorting single-walled carbon nanotubes according to their diameters and chirality.However,these methods generally suffer the complicated and high-cost experimental processes.Owing to its low cost and good controllability,the chemical vapor deposition technique has shown a broad application prospect in growing single-walled carbon nanotubes with narrow chirality distribution and has been recognized as the ideal method for single-walled carbon nanotube bulk synthesis.The catalyst plays crucial roles in regulating the nucleation thermodynamics and growth kinetics of single-walled carbon nanotubes.With the aim to realize the selective growth of single-walled carbon nanotubes,the first critical step is to design and prepare a suitable catalyst.The powder catalyst has shown great potential in single-walled carbon nanotube bulk synthesis due to their larger surface area,which can provide substantial catalytic active substances during the chemical vapor deposition process.Moreover,the strong interaction between the support and catalytic particles ensures the uniform dispersion of the catalytic active substance and avoids the sintering and deactivation of the catalytic particles.Therefore,the chirality of single-walled carbon nanotubes grown by powder catalyst can be controlled on the premise of guaranteeing the yield.Nowadays,most of the powder catalysts are composite oxides.The layered double hydroxide is a kind of synthetic anionic clay,which can be reduced to form uniformly distributed metal particles on the thin sheet.Thus,the layered double hydroxide can be used as an excellent catalyst for the growth of single-walled carbon nanotubes.In addition,magnesium oxide is a commonly used supported catalyst.Its large specific surface area and good interaction with metal catalyzed particles make it widely used in the growth of carbon nanotubes.Based on this background,the main research of this work is as following:(1)An iron-based layered double hydroxide catalyst was designed to grow carbon nanotubes by chemical vapor deposition using carbon monoxide as carbon source.The results show that cobalt doping can effectively reduce the growth temperature of carbon nanotubes and achieve the growth of narrow chiral distribution of single-walled carbon nanotubes.Subsequently,the(6,5)single-walled carbon nanotubes were enriched by two-phase aqueous extraction.This work not only extends the applications of layered double hydroxides in catalyzing single-walled carbon nanotubes growth,but also provides useful insights into catalyst activation and single-walled carbon nanotubes nucleation,which would ultimately help the growth of single-walled carbon nanotubes with narrowly distributed chirality distribution,paving the way towards applications where single-walled carbon nanotubes with uniform structures are needed.(2)Single-metal layered double hydroxide catalyst of cobalt-based and nickelbased was designed to grow single-walled carbon nanotubes by chemical vapor deposition using carbon monoxide as carbon source.The effects of metal carbon solubility and catalyst interfacial interaction on the chirality distribution of single-walled carbon nanotubes were systematically investigated.This work not only achieves the growth of single-walled carbon nanotubes with narrow chirality distribution,but also contributes to the in-depth understanding of the catalyst activation mechanism of the growth of single-walled carbon nanotubes.(3)A magnesium oxide supported cobalt and copper bimetallic catalyst was designed to grow carbon nanotubes by chemical vapor deposition using carbon monoxide as carbon source.The effects of metal ratio and growth temperature on chirality distribution of single-walled carbon nanotubes were systematically studied.This work provides a research idea for the development of chiral selective growth of SWNTs by supported bimetallic catalysts,deepens the synergistic catalytic effect of bimetals,and provides a reference for the realization of chiral selective growth of singlewalled carbon nanotubes.