Novel Sieverts’ type volumetric measurements of hydrogen storage properties for very small sample quantities

Novel volumetric analysis instrument for studying hydrogen storage property of very small quantities (∼mg) of samples was developed and tested. Small pressure change arising from hydrogen uptake or release are precisely measured and equated to the change in the sample's hydrogen content using the gas law equation. Very small volume pressure reservoir enables these precise measurements, and all internal volumes are calibrated with high-purity helium gas. Capacity, equilibrium isotherm, and kinetic measurements can be performed in the pressure range of vacuum to 4 MPa and the temperature range from cryogenic-673 K. Test measurements were made on small carbon nanotube samples and measurement of less than ∼3 μg of hydrogen uptake was demonstrated, which corresponds to an accuracy of better than 0.15 wt% for a 2 mg sample.