Control of Selectivity in Heterogeneous Photocatalysis by Tuning TiO2 Morphology for Water Treatment Applications

Heterogeneous photocatalysis using TiO2 is a non-selective technique used for the degradation of organic molecules. Controlling the morphology of TiO2 has recently been considered one of the important approaches for controlling the selectivity of TiO2. In this work, TiO2 nanotubes and nanosheets were synthesized from spherical TiO2 nanoparticles using the hydrothermal method. The starting and prepared samples were characterized by XRD, TEM and FESEM. The selectivity of the three morphologies towards the photocatalytic degradation of three food dyes (colours yellow sunset, red allura and red carmoisine) was tested. Importantly, changes in morphology led to each dye being adsorbed preferentially by one of the three morphologies and decomposing more rapidly, where the optimum rate of degradation for sunset yellow, red allura and red carmoisine was achieved by TiO2 nanosheets, spherical TiO2 and TiO2 nanotubes, respectively.