Morphological evolution of hierarchical nickel titanates by elevation of the solvothermal temperature

In this study, the morphological evolution of hierarchical nickel titanates was first-ever investigated by simply raising the solvothermal temperature. At room temperature, irregular aggregates of anatase TiO2 nanoparticles were reluctantly formed. Increasing the temperature to 100 °C resulted in the assembly of 3D drum-shaped nickel titanate clusters where the three-dimensional geometry was constructed via coalescent nanoparticles with a mean size of 126.8 nm. An intermediate stage containing circular cylinders and irregular prisms was obtained at intermediate temperatures. Further elevation of the solvothermal temperature to 160 °C and 180 °C gave 1D uniform hexagonal nanoprisms of nickel titanates. Increasing the solvothermal temperature accelerates the nucleation rate, which drastically promotes crystallization and self-assembly, thereby evolving to the hierarchical structure of NiTiO3.