Comparison of SiO2/TiO2 photocatalysts with different thicknesses synthesized by fluidized bed atomic layer deposition

SiO 2 /TiO 2 core/shell particles are effective photocatalysts, whose performance strongly depends on TiO 2 film thicknesses. Fluidized bed atomic layer deposition (FBALD) can precisely control film thickness at the sub-nanometer scale. In this work, TiO 2 films with different thicknesses are deposited on SiO 2 particles via different ALD cycles at 180 °C in a fluidized bed reactor. TEM images indicate that complete and uniform nanoscale TiO 2 films (0.7–6.4 nm, corresponding to 5–50 ALD cycles) are formed on SiO 2 surface. The TiO 2 film with about 3.9 nm is found to exhibit the highest photocatalytic characteristics by degrading rhodamine-B (RhB) and tetracycline (TC), and the photocatalytic activity is further maintained above 90% after 6 cycles of photocatalytic reaction. Suitable TiO 2 film thickness shows minimal charge transfer resistance, resulting in enhanced photon adsorption and separation of electrons and holes, thus improving photocatalytic performance. This work provides an effective way to tune the photocatalytic performance via FBALD.