Physical properties optimization of carbon nanotubes from palm oil precursor

Carbon nanotubes (CNT) were synthesized from palm oil as carbon source using thermal chemical vapor deposition method (TCVD). The parametric studies were carried out to determine the optimum parameters to produce CNT with the optimum physical properties. The parameters comprise of synthesis temperature, catalyst concentration, substrate positions, precursor amount, synthesis time, carrier gas and variety of bio-hydrocarbon precursors. The physical properties of CNT were analyzed using electron microscope, energy-dispersive X-ray analysis, micro-Raman and Fourier transform infrared (FTIR) spectroscopy, thermogravimetric (TGA) and CHNS-O analyser as well as four point probe for IV measurement. The carbon precursor was also analyzed using TGA, FTIR spectroscopy and gas chromatography mass spectrometry (GC-MS) in order to optimize the physical properties of CNT. The findings revealed that the synthesis parameters have significant influence on the synthesized CNT. Based on the analysis, well-aligned CNT with uniform diameters (23.4-28.4 nm), high purity (85.93 %) and crystallinity (ID/IG = 0.54) were successfully produced from 6 ml of palm oil precursor at 750 oC synthesis temperature, 5.33 wt% catalyst concentration at P3 substrate positions within 60 minutes synthesis time in argon ambient. The formulation of CNT growth mechanism produced from palm oil on the important parameters such as the effect of synthesis temperature, catalyst concentrations as well as the effect of carrier gas were proposed. In term of electrical properties, the CNT from palm oil has the highest conductivity of 3612.59 S.cm-1 as compared to other samples produced from variety of biohydrocarbon precursors. From the IV characteristics, it shows that the metal contact helps to increase the electrical conductivity of the samples. The field electron emission (FEE) equipment was used to determine the FEE properties of CNT. From the FEE analysis, the CNT from palm oil was able to emit electrons at the lowest fields of 2.64 V.μm-1 and reach highest maximum current of 15.07 mA.m-2. It can be concluded that the optimum physical properties of palm oil based CNT were successfully produced by TCVD method with potential application as field emitting devices.