Synthesis and hydrogen storage properties of carbon nanotubes

Multi-walled carbon nanotubes (MWNT) have been synthesized by chemical vapor decomposition of acetylene over rare-earth (RE) based AB2AB2 alloy hydride catalysts. The AB2AB2 alloy hydride catalysts have been prepared by hydrogen decrepitation technique and characterized by scanning electron microscopy. The advantage of this novel method of obtaining catalysts has been discussed. The as-grown carbon nanotubes were purified by acid and heat treatments and characterized using powder X-ray diffraction, transmission electron microscopy, scanning electron microscopy, thermo gravimetric analysis and Raman spectroscopy. Hydrogen adsorption measurements were carried out on as-prepared and purified MWNT in the temperature range of 143–373 K and pressure range of 10–100 bar using a high pressure hydrogen adsorption setup and the results have been discussed. A maximum hydrogen storage capacity of 3.5 wt% is obtained for purified MWNT prepared with DyNi2DyNi2 alloy hydride catalyst at 143 K and 75 bar.