Hindawi Publishing Corporation Journal of Nanomaterials Volume 2013, Article ID 105145, 13 pages http://dx.doi.org/10.1155/2013/105145 Research Article Multiwalled Carbon Nanotube Synthesis Using Arc Discharge with Hydrocarbon as Feedstock K. T. Chaudhary, 1 Z. H. Rizvi, 1 K. A. Bhatti, 2 J. Ali, 1 and P. P. Yupapin 3 1 Institute of Advanced Photonics Science (APSI), Nanotechnology Research Alliance, Universiti Teknologi Malaysia, 81310 Johor Bahru, Malaysia 2 Physics Department, University of Engineering and Technology, Lahore 54000, Pakistan 3 Nanoscale Science and Research Alliance (N’SERA), Faculty of Science, King Mongkut’s Institute of Technology Ladkrabang, Bangkok 10520, Tailand Correspondence should be addressed to K. T. Chaudhary; kashif.ali02@gmail.com Received 1 July 2013; Revised 23 October 2013; Accepted 16 November 2013 Academic Editor: Xuedong Bai Copyright © 2013 K. T. Chaudhary et al. Tis is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Synthesis of multiwalled carbon nanotube (MWCNT) by arc discharge process is investigated with methane (CH 4 ) as background and feedstock gas. Te arc discharge is carried out between two graphite electrodes for ambient pressures 100, 300, and 500 torr and arc currents 50, 70, and 90 A. Plasma kinetics such as the density and temperature for arc discharge carbon plasma is determined to fnd out the contribution of physical parameters as arc current and ambient pressure on the plasma dynamics and growth of MWCNT. With increase in applied arc current and ambient pressure, an increase in plasma temperature and density is observed. Te synthesized samples of MWCNT at diferent experimental conditions are characterized by transmission electron microscopy, scanning electron microscopy, Raman spectroscopy, Fourier transform infrared spectroscopy, and X-ray difraction. A decrease in the diameter and improvement in structure quality and growth of MWCNT are observed with increase in CH 4 ambient pressure and arc current. For CH 4 ambient pressure 500 torr and arc current 90 A, the well-aligned and straight MWCNT along with graphene stakes are detected. 1. Introduction Te unique structure of carbon nanotube (CNT) exhibits extraordinary electronic, thermal, and mechanical properties [1] which make them potential candidate for diferent techno- logical applications [2–4]. Extensive eforts have been done to synthesize structured-controlled CNT. Several methods have been developed to synthesize CNT such as arc discharge [5], chemical vapor deposition (CVD) [6], and laser ablation [7]. Among these methods, arc discharge method is the promising technique capable to fabricate high quality CNT [8–10]. However, the control growth of CNT has not been accomplished due to lack of control and limited understand- ing of arc discharge plasma. A high infux of plasma species and high temperatures play key role in the growth of nanos- tructures. In order to realize and optimize the application of CNT, it is desired to understand the growth mechanism and infuence of physical parameters (as ambient pressure, electrode geometry, applied current and voltage, gas fow, inter electrode distance, dynamics of plasma species, etc. [11]) on the growth of nanostructures. Te arc current, ambient gas, and ambient pressure are the important parameter for arc discharge synthesis of MWCNT. Te arc current supplies energy to anode causing the evaporation of anode surface and formation of arc plasma. Te MWCNT with diameters largely distributed in the range of 40–60 nm are observed for arc discharge in absence of ambient gas. During arc discharge evaporation, the ambient gas acts as bufer gas and infuence the growth and diameter distribution of MWCNT [12, 13]. Te arc discharge process for the synthesis of MWCNT is studied in diferent environments to control and improve their growth. For instance, in helium and argon environment the diameter distribution goes higher by varying the gas mixture from argon to helium and an average decrease in