Pd-doped double-walled silica nanotubes as hydrogen storage material at room temperature

Palladium-doped double-walled silica nanotubes (SNTs) were synthesized by sol-gel transcription, and H-2 adsorption experiments were carried out at 298 K. The H-2-storage capacities of the palladium-doped SNTs were 0.15 wt % for SNT-5, 1.90 wt % for SNT-10, and 0.75 wt % for SNT-15, showing that the palladium-doped tubes are very effective as an H-2-storage material even at room temperature. Remarkably, SNT-10 had the highest storage capacity. The results indicate that palladium nanoparticles acted as the primary receptor for adsorption of atomic hydrogen. Also, this finding suggests that a moderate amount of palladium nanoparticles is important to effectively uptake H-2 in the nanotubes. We suggest that palladium-doped double-walled SNTs are useful as H-2-storage materials in fuel cells.