Synthesis of core-shell nanostructured SiO2/TiO2 photocatalysts via atomic layer deposition in a fluidized bed with central tube

Fluidized bed atomic layer deposition is an efficient technique for particle coating with precise control over the film thickness and uniformity at the sub-nanoscale. In this study, a fluidized bed with a central tube is designed, where the central tube has two roles: improve fluidization and deliver precursors separately. The synthesis of core-shell structured SiO2/TiO2 nanoparticle catalysts for photodegradation of tetracycline hydrochloride (TC) is carried out using TiCl4 and H2O as precursors at 180 °C under atmospheric pressure. Under the combination of vibration and central tube, the segregation of agglomerate size along the bed height is weakened, and the prepared SiO2/TiO2 nanoparticles show excellent photocatalytic degradation performance: the degradation efficiency on TC is 96% under 300 W xenon lamp irradiation for 60 min. The mechanism of enhanced photocatalytic activity is due to the Ti-O-Si bonds generated at the interface, which increase the ability to absorb sunlight and accelerate the separation of holes and electrons.