Hydrothermal synthesis and characterisation of potassium/sodium titanate nanofibres at different temperatures

Various sized nanofibres (800 nm - 5 μm in length and 15-50 nm in diameter) and nanosheets are synthesised from anatase powder (particle size; 300 400 nm) using a simple hydrothermal approach in the concentrated KOH and NaOH mixed solution. The products are analysed by a range of methods including powder X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy and UV-vis spectrophotometer. It is found that the morphologies of titanate strongly depend on the hydrothermal temperature, in which alkali plays an important role during the whole process. The result shows that the reaction activity of NaOH with TiO₂ is better than that of KOH, because the radius of K (1.33 Å) is significantly larger than that of Na (0.97 Å). The aspect ratio of the products becomes larger with the increase of the KOH concentration. Furthermore, with the size decrease of the titanate nanofibres samples, the results show that their UV-vis spectra are blue-shift obviously. This work has provided an effective method to synthesise titanate composite nanofibres in alkali solution, which may also be applicable to the preparation of other composite nanomaterials.