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 AB 2 alloy hydride catalysts. The AB 2 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 DyNi 2 alloy hydride catalyst at 143 K and 75 bar.