Morphology, size control, and photocatalytic activities of titanium dioxide nanoparticles synthetized by microemulsion method

In the present work, we successfully synthesized titanium dioxide nanoparticles (TiO2-NPs) by reverse microemulsion method using cyclohexane, aqueous ammonia materials, and various ratios of surfactants. Using this method, nanoparticles of various morphologies, such as filamentous, sheet, and spherical morphologies, were synthesized. In addition, NPs in very small size (i.e., 4–7 nm for spherical morphology) were obtained. The as-prepared samples showed light absorption in the range of 200–300 nm, indicating their potential application as an UV light induced photocatalyst. The obtained TiO2-NPs were amorphous and can be converted to anatase by heating at 600–750 °C and to rutile by heating above 900 °C. In addition, TiO2-NPs with sheet morphology showed the highest activity on photocatalytic decomposition of methyl orange relative to spherical and filamentous morphologies. We also showed that doping of tin (Sn) atoms in TiO2-NPs causes a significant increase in the photocatalytic activity of NPs and the time needed for photocatalytic decomposition decreases to around one-fifth of the time needed for nondoped NPs. The results of the present research indicated that the microemulsion process is an effective/potential method for the synthesis of some new functional materials.