Synthesis of hollow TiO2 nanobox with enhanced electrorheological activity

TiO2 nanoboxes with a hollow interior space, derived from titanium oxydifluoride (TiOF2) nanocubes, were prepared using a two-step method, in which the TiOF2 nanocubes acting as the precursor were first synthesized using a typical hydrothermal route. Subsequently, a second hydrothermal step was developed to prepare the TiO2 nanoboxes. The clear phase transformation from the TiOF2 precursor to anatase TiO2 was confirmed using X-ray diffraction, Fourier-transform infrared spectroscopy, and X-ray photo-electron spectroscopy analyses. The evolution of the morphology from a nanocube to nanobox was revealed by scanning electron microscopy and transmission electron microscopy observations. The influences of the phase and morphology on the electrorheological (ER) effect were investigated using an ER test. The ER results suggested that the ER efficiency was significantly enhanced after the second hydrothermal treatment, especially under a high external electric field strength. The enhancement in the ER efficiency was further studied using a dielectric spectrum analysis. It demonstrated that the faster response time and large permittivity difference obtained from the dielectric spectrum of TiO2 were responsible for the improvement in the ER effect.