Simulation for growth of multi-walled carbon nanotubes in electric field

An electric field was introduced for producing multi-walled carbon nanotubes (MWCNTs) in flames and it was found that a low biased voltage was enough to synthesize well-aligned MWCNTs. Finite element method was adopted to simulate the growth of MWCNTs in electric field and calculate the electrostatic forces acting upon MWCNT itself and the catalyst particle at the MWCNT tip. The numerical results revealed that: (1) the electrostatic repulsive force induced by the similar charges of neighboring MWCNTs is strong and favorable to overcome van der Waals force, which consequently is a main factor to align MWCNTs; (2) the electrostatic attractive force along the field direction acting on the catalyst particle at MWCNT tip is much larger than that on the tube, which plays a key role for vertical growth of MWCNTs; (3) the value of the electrostatic attractive force acting on the nanotube and catalyst particle is related to height, density and diameter of MWCNTs.