Characterization and Hydrogen Storage Performance of Halloysite Nanotubes.

Here we report on the structural characterization and the hydrogen storage performance of naturally derived halloysite nanotubes (HNTs). HNTs were mined from different deposits in Australia and purified with different processes including crushing, blunging, reblunging, sedimentation and filtration. The clay materials were characterized by different techniques such as powder XRD, TGA, XPS, FTIR spectroscopy, SEM, TEM, and N₂ sorption. Characterization results revealed that they are highly porous in nature with tubular morphology and exhibited excellent thermal stability. Among the halloysite materials studied, HNT1 which is having higher halloysite content and less kaolinite exhibited hydrogen uptake of 0.5 wt.% at 1 bar and -196 °C, which is increased to 1.33 wt.% when the pressure raised to 48 bar. High hydrogen uptake was linked with the high surface area, hollow tubular aluminosilicate structure and the large interlayer spacing of the HNTs as they favour physisorption of hydrogen. It was also demonstrated that HNT1 is considered to be better material than some of the materials reported so far in terms of their cost-effectiveness and environmental safety for the hydrogen storage.