Hydrogen storage properties of Pd-doped thermally oxidized single wall carbon nanohorns.

Single wall carbon nanohorns as well as their thermally oxidized derivatives were decorated with Pd nanoparticles and their H2 sorption performance was examined at 298 K up to 20 bar. The specific surface area of the nanohorns was increased through air oxidation, while both the thermal treatment and the metal doping led to the enhancement of the H2 uptake. The higher uptake of the hybrid materials could not be attributed only to the additive effect of the carbon support and Pd content suggesting the existence of a cooperative mechanism between the metal particles and the carbon surface. This weak chemisorption process was found to be fully reversible after mild heating; still, its contribution to the overall H2 uptake was not found to be of great significance.