Crystallite phase-controlled preparation, characterisation and photocatalytic properties of titanium dioxide nanoparticles

A solution-based processing method has been used to synthesise nanostructured titanium dioxide (TiO₂) with different crystalline forms ratio (anatase, rutile and their mixtures) by controlling the hydrolysis of titanium tetrachloride in aqueous solution. The contents of anatase and rutile phases in the synthesised TiO₂ powders have been successfully controlled by simply changing the proportion of SO^2-₄ in the aqueous phase. The prepared materials were characterised by X-ray diffraction, transmission electron microscopy, scanning electron microscope and Brunauer-Emmett-Teller techniques. The experimental results showed that the average size of the synthesised particles was in the range of 6-11 nm. The photocatalytic performance of the synthesised TiO₂ nanoparticles was evaluated by removal of the dye, C. I. Acid Blue 9 (AB9), under UV light illumination (30 W). According to the results, rutile appeared to be a poor photocatalyst while the mixed-phase TiO₂ (rutile-anatase) demonstrated the highest photoactivity. The efficiency parameters such as apparent quantum yield and electrical energy per order were estimated and compared for different crystalline forms of TiO₂. It was found that the photocatalysis process with synthesised mixed-phase TiO₂ nanoparticles, containing 70% anatase, had lower electrical energy consumption and higher quantum yield compared with others.