Synthesis of TiO₂ Tubes Via Dissolution of TiOSO₄ Rod Using H₂O₂

We demonstrate here for the first time an original and facile approach to preparing titanium oxide (TiO₂) tubes using hydrogen peroxide (H₂O₂) and titanyl (IV) oxysulfate (TiOSO₄) as sacrificial templates. The method involves dissolving TiOSO₄ powder in H₂O₂ solution and subsequently applying thermal treatment on the resulting amorphous precipitate. Prepared samples were characterized by X-ray diffraction, scanning electron microscopy (SEM) images, thermogravimetric (TG) analysis, and UV-vis analysis. Experimental results indicated that the samples exhibit tube-like structures with lengths of approximately 1.9 mm in diameter and 11.5 mm in length. Anatase and rutile phases were formed after annealing at different temperatures in air. The crystallite size estimated by Rietveld refinement showed an increase from 34.69 to 354.28 nm with an increase in the annealing temperature from 600 to 1000 °C. At the same time, the band gap values decreased from 3.14 to 2.97 eV. The electron density maps were calculated, and the electronic density was observed to increase from 497.56 e^- Å^-2 (600 ^°C) to 533.10e^- Å^-2 (740 ^°C) and decrease with the annealing temperature of samples. A possible mechanism for the formation of TiO₂ tubes was proposed.

Keywords:
TiO₂ tubes; titanyl sulfate; template-free; sacrificial template