One-step preparation of TiO2 particles with controllable phase and morphology by plasma electrolysis

Abstract

TiO₂ particles were prepared by plasma electrolysis with a one-step method in aqueous solution. By adjusting the Ti(SO₄)₂ concentration, the phase and morphology of the synthesized particles were well controlled. When Ti(SO₄)₂ concentration was in the range of 0.1–0.3 mol L⁻¹, TiO₂ particles with anatase as the main phase were obtained. From transmission electron microscopy (TEM) and inverse fast Fourier transform (FFT) analysis results, the average grain size of the particles was found to be about 4.0–6.0 nm, which was in accordance with X-ray diffraction (XRD) results. Micrographs showed that the surface of the particles obtained in the low concentrations was rough and composed of tiny nano-structures (about 10 nm). With increase of the concentration, the main phase of the TiO₂ particles was transformed from anatase to rutile and the grain size became bigger, while particle size became smaller and the surface of the particles was smoother. When the concentration was higher than 0.6 mol L⁻¹, TiO₂ particles with rutile as the main phase were synthesized. The average grain size of the anatase increased to 30.0–50.0 nm, and the rutile's size was about 60.0–75.0 nm. By measuring the current density–time curves, the effect of concentration on phase and morphology of the particles has been explained. The function of the cathode material and the generation of TiO₂ particles have also been discussed, after analyzing the compositions, microstructure and weight of cathode material before and after plasma electrolysis.