Structural characterization and effect of dehydration on the Ni-doped titanate nanotubes

Titanate nanotubes and Ni-doped titanate nanotubes were synthesized by hydrothermal method and simple firing using rutile powders as starting materials. The hydrogen absorption of the nanotubes was investigated by the conventional volumetric pressure-composition (P-C) isothermal method using an automated Sivert's type apparatus. The microstructure and morphology of the synthesized nanotubes were characterized by X-ray diffraction (XRD), high resolution transmission electron microscopy (HR-TEM). Titanate nanotubes compose of H₂Ti₂O₅·H₂O in accordance with DFT (Density Functional Theory) calculation and has outer and inner diameter of ∼10 and 6 nm, and the interlayer spacing about 0.65-0.74 nm. The storage capacity of hydrogen in the Ni-doped nanotubes increased linearly with pressure and revealed reliable evidence of hydrogen sorption at room temperatures.