Hydrogen storage in carbon nanotubes: Residual metal content and pretreatment temperature

Hydrogen storage in MWNT was enhanced via the catalytic activity of NiMgO. The magnitude of the hydrogen to metal ratio for the MWNT/NiMgO system, combined with temperature programmed adsorption and desorption studies, showed hydrogen spillover from the catalyst to the carbon surface. Metal doping combined with temperature activation studies showed that both nickel and magnesium are active in the catalytic process. The yield, quality, and carbon-metal contact were shown to affect hydrogen uptake. Higher pretreatment temperatures enhanced uptake, for both low- and high-pressure measurements, due to increased carbon-metal contact and activation of the catalyst. At 69 bar (or 1,000 psia), the hydrogen adsorption and desorption of the MWNT/NiMgO system were 3.7% and 3.6%, respectively.