Hierarchical β-Ni(OH)2 nanostructures composed of ultrathin nanosheets were synthesized via a hydrolytic process of nickel chloride. The obtained samples were characterized by X-ray diffraction, thermal gravimetric, scanning electron microscopy, transmission electron microscopy and X-ray photoelectron spectrometer. The corresponding results show that the Ni(OH)2 has a β-phase structure, and the hierarchical β-Ni(OH)2 nanostructures are made up of several cross-linked nanosheets, and the thickness of the nanosheets is only 9.3nm. The ultrathi...