Role of Bridging Oxygen Vacancy on Reduced Anatase TiO2 (101) for Photodegradation of Rhodamine-B

Abstract

A hydrothermal method is proposed for the synthesis of TiO2 nanoparticles, which were further sintered at 200 °C, 300 °C, 500 °C, and 800 °C in a hot air oven. UV–light-driven photodegradation of Rhodamine-B dye was studied for as-prepared and sintered samples. The low probability of recombination of electron-hole pair and high charge separation rate showed better performance in degradation efficiency for a sample sintered at 300 °C. X-ray diffraction patterns suggest that as the sintering temperature is increased, amorphous nature vanishes and a pure anatase phase is observed. With a further increment of sintering temperature above 300 °C, mixed phase is observed. Band bending phenomenon of anatase and rutile provides a clear view on photocatalytic performance. Kinetics and mechanism of adsorbed water molecules with the bridging oxygen vacancy and 5 fold coordinated titanium (Ti5c) of reduced anatase TiO2 (101) is illustrated schematically, where energy is reduced in the presence of bridging oxygen vacancy. The concept of oxygen vacancies and water molecule adsorption over reduced titania surface is discussed. The reaction mechanism process of the kinetics of the adsorbed water molecules with the bridging oxygen vacancy defects and Ti5c site along the bridging and terminal hydroxyl radical are embedded on reduced TiO2 (101) nanoparticles.