Growth of Single-Walled Carbon Nanotubes with Rh and Cu Catalysts

Currently the most widely used method for the growth of carbon nanotubes is the catalytic chemical vapor deposition (C-CVD). In this method, a transition metal nanoparticle is used as the catalyst. The nanoparticle is either supported onto a surface or unsupported and floating. Recently, the growth of CNT from the system of Co-Mo supported by MgO was explored using Environmental Scanning Transmission Electron Microscope (ESTEM) [1]. In the computational front, the potential of Ni nanoparticles as the catalyst for C-CVD has been studied using DFT and ab initio molecular dynamics (AIMD) simulations [2]. Apart from the traditional Fe, Co and Ni, other transition metals have also been shown to exhibit unique characteristics in terms of decomposing carbon feed gas, dissolving carbon, possessing reasonable strength of metal-carbon bonds, and forming graphitic caps on their surface that could be advantageous for more practical temperature and pressure ranges [3]. In another study [4], Cu has been suggested to be an appropriate catalyst, although for graphene synthesis, due to its low diffusion and nucleation barrier towards carbon.

Subsequently, in this work, using DFT and AIMD simulations we investigate and compare two transition metals Cu and Rh, both of which have low solubility towards carbon. The study is conducted for supported and unsupported nanoparticles. The dissolution of carbon in different sizes of metal nanoparticles is studied. These carburized metal nanoparticles are then brought into contact with graphene fragments and CNT caps with certain chirality to study the interaction and energetics between them. Finally, AIMD simulations of these systems will reveal their dynamics and the changes, if any, in the chirality of these caps. In conclusion, this will shed light on the effect of low carbon-dissolving transition metals on CNT chirality and geometry as possible catalysts for CNT growth.

References

 [1] Picher, M., Lin, P.A., Gomez-Ballesteros, J.L., Balbuena, P.B., Sharma, R., ‘Nucleation of graphene and its conversion to single-walled carbon nanotubes’, Nano letters 14(11): 6104-6108 (2014)

[2] Gomez-Ballesteros, J.L., Balbuena, P.B., ‘Structure and dynamics of metallic and carburized catalytic Ni nanoparticles: effects on growth of single-walled carbon nanotubes’, Phys. Chem. Chem. Phys. 17: 15056-15064 (2015)

[3] Silvearv, F., Larsson, P., Jones, S., Ahuja, R., Larsson, A., ‘Establishing the most favorable metal–carbon bond strength for carbon nanotube catalysts’, J. Mater. Chem. C 3: 3422-3427 (2015)

[4] Li, J., Croiset, E., Ricardez-Sandoval, L., ‘Effects of metal elements in catalytic growth of carbon nanotubes/graphene: A first principles DFT study’, Applied Surface Science 317: 923–928 (2014)