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 Sivertʹs 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.