Morphological study of carbon nanotubes synthesised by FCCVD

Carbon nanotubes (CNTs) were produced using chemical vapour deposition fabricated at the Department of Chemical and Environmental Engineering, Universiti Putra Malaysia. The CNTs were characterised using TEM and ASAP 2000 micromeritics. Typical adsorption isotherms of all the samples obtained from the BET analysis showed hysteresis indicating capillary condensation of N2 in all samples with highest amount adsorbed on SP2, 131 cm3/g STP followed by SP1, 111 cm3/g STP. In characterising with methane as adsorbate a typically small intermolecular distance, of r = 0.4 nm was obtained, the intermolecular potential energy due to repulsion for adsorption was 5.23 kJ/mol being less than desorption potential energy of 6.75 kJ/mol. At equilibrium separation, r0 = 0.48 nm, well depth, ε = 2.65 × 10−21 J, the intermolecular potential energies for methane adsorption and desorption were −1.60 and −1.43 kJ/mol respectively. Isosteric heats of adsorption and desorption obtained were −2.68 and −1.30 kJ/mol, respectively, where the negative signs signify heat released. These results involving intermolecular repulsion, attraction and bond strengths signify phase co-existence during adsorption/desorption. Evaluated parameters, ε, σ, ε/k, r0, and isosteric heats parameters were convincingly comparable with literatures.