Kinetic study of boron doped carbon nanotubes synthesized using chemical vapour deposition

Abstract

Boron doped carbon nanotubes were synthesized using chemical vapour deposition using acetylene as carbon source, boric acid as boron source and Ferrocene/MgO as catalyst/support. Boric acid was directly used as a solid precursor for doping boron in the CNT lattice. A kinetic model was established by varying the temperature of the reactor, partial pressure of reactants, flow rates and catalyst concentration. The rate controlling steps were studied and the optimal reaction conditions were established so as to synthesize the desired quantity and quality of boron doped carbon nanotubes. Boron doping of 6.31–6.71 at.% was obtained. Two different mechanisms were found to control the rate of reaction at different range of temperatures. The activation energy for the two mechanisms was found to be 18.21 kJ/mol and 6.73 kJ/mol respectively. A mechanism was proposed and validated using the experimental data so as to understand the growth of B-CNTs. The synthesized B-CNTs were purified using concentrated hydrochloric acid and characterized by using SEM, TEM to understand the surface characteristics; FTIR and XPS to detect and quantify the boron present in the sample, Raman spectroscopy and TGA analysis to determine the purity of the product.