Hydrogen storage: a comparison of hydrogen uptake values in carbon nanotubes and modified charcoals

We compared the hydrogen uptake weight percentages (wt.%) of different carbonized materials, before and after modification, for their application in hydrogen storage at room temperature. The Sievert's method [T.P. Blach, E. Mac, A. Gray, J. Alloys Compd. 446-447, 692 (2007)] was used to measure hydrogen uptake values on: (1) Taiwan bamboo charcoal (TBC), (2) white charcoal (WC), (3) single-walled carbon nanotubes (SWCNTs) bought from CBT Inc. and (4) homemade multi-walled carbon nanotubes (MWCNTs) grown on TBC. Modified samples were coated with a metal catalyst by dipping in KOH solutions of different concentrations and then activated in a high temperature oven (800 degrees C) under the atmospheric pressure of inert gas. The results showed that unmodified SWCNTs had superior uptake but that Taiwan bamboo charcoal, after modification, showed enhanced uptake comparable to the SWCNTs. Due to TBC's low cost and high mass production rate, they will be the key candidate for future hydrogen storage applications.