Epitaxial growth route to crystalline TiO₂ nanobelts with optimizable electrochemical performance

Anatase TiO₂ nanobelts with 13 nm in thickness have been successfully synthesized via an epitaxial growth chemical transformation, in which the primary H₂Ti₃O₇ nanobelt frameworks can be preserved. The phases, crystal structures, morphologies, and growth behavior of both the precursory (Na₂Ti₃O₇ and H₂Ti₃O₇) and resultant products (TiO ₂) are characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and selected area electron diffraction (SAED). Detailed investigation of the formation mechanism of the TiO₂ nanobelts indicates epitaxial nucleation and oriented growth of textured TiO₂ inside the nanobelts. TiO ₂ nanocrystals prefer certain epitaxial growth direction due to the structural matching of (110)_H2Ti3O7//(101)_TiO2. We demonstrated that the initial reversible capacity of these TiO₂ nanobelts attained 225 mA h/g. Furthermore, the nanobelts exhibit high power density along with excellent cycling stability in their application as hybrid electrochemical cells.