Growth of Wall-controlled MWCNTs by Magnetic Field Assisted Arc Discharge Plasma

Carbon nanotubes have long attracted great scientific interest because of their simplicity, ease of synthesis and unique properties. The novel properties of nanostructured carbon nanotubes including its high surface area, stiffness, tensile strength, thermal and electrical properties which become suitable for the application in the fields of energy storage, hydrogen storage, electrochemical supercapacitor, field-emitting devices, transistors, nanoprobes and sensors, composite material, templates, etc. In this study, carbon nanotubes were synthesized through arc discharge plasma with two different configurations, transverse and axial field, applied across arc plasma synthesis process to enable a much rapid rate growing of tubular carbon multi-walled carbon nanotubes (MWCNTs). TEM, FESEM, RAMAN, FTIR and XRD were used to investigate the morphology and structural evolution of the MWCNT samples produced with different synthesis environment. Introduction of magnetic field during the MWCNTs synthesized through arc discharge plasma technique has also been found to enhance the carbon nanotube growth, increase the high aspect ratio and its chemical stability, and shows potential for regulating the number of walls formed.     

Investigation on the electrochemical performances of Li<Subscript>4</Subscript>Mn<Subscript>5</Subscript>O<Subscript>12</Subscript> for battery applications

In this study, well-crystallized Li₄Mn₅O₁₂ powder was synthesized by a self-propagating combustion method using citric acid as a reducing agent. Various conditions were studied in order to find the optimal conditions for the synthesis of pure Li₄Mn₅O₁₂. The precursor obtained was then annealed at different temperatures for 24 h in a furnace. X-ray diffraction results showed that Li₄Mn₅O₁₂ crystallite is stable at relatively low temperature of 400 °C but decompose to spinel LiMn₂O₄ and monoclinic Li₂MnO₃ at temperatures higher than 500 °C. The prepared samples were also characterized by FESEM and charge-discharge tests. The result showed that the specific capacity of 70.7 mAh/g was obtained within potential range of 4.2 to 2.5 V at constant current of 1.0 mA. The electrochemical performances of Li₄Mn₅O₁₂ material was further discussed in this paper.