Hydrogen Spillover from a Metal Oxide Catalyst onto Carbon Nanotubes—Implications for Hydrogen Storage

Hydrogen storage on multiwalled nanotubes (MWNTs) was dependent on the degree of catalyst removal. At atmospheric pressure, removal of the catalyst decreased the uptake from 0.6% to below detection limits. Hydrogen uptake of the metal oxide catalyst ranged from 0.25 to 0.98%, depending on surface area. Normalization by metal content and temperature-programmed desorption studies suggest hydrogen dissociation and subsequent spillover to the MWNT. Metal-support interactions were key to the spillover; dry mixing of the MWNT and catalyst did not enhance storage, whereas in situ production increased storage by 40%. The moderate temperature range of this material suggests a novel material for hydrogen storage applications.