Application of pulsed chemical vapor deposition on the SiO2-coated TiO2 production within a rotary reactor at room temperature

Pulsed chemical vapor deposition (P-CVD) is a promising technology for the surface modification of TiO₂ particles. For the scale-up application of P-CVD, a custom-designed rotary reactor and corresponding coating process at room temperature was developed in the present work. The obtained SiO₂-coated TiO₂ particles were characterized by various measures including high-resolution transmission electron microscope, Fourier transform infrared spectroscopy, X-ray diffraction, etc. The results illustrated that the SiO₂ films with a thickness of (3.7 ±0.7) nm were successfully deposited onto the surface of TiO₂ particles. According to the dye degradation tests and acid solubility measurement, the deposited film can effectively inhibit the photocatalytic activity and enhance the weatherability of the TiO₂ particles. Zeta potential measurements showed that the SiO₂-coated TiO₂ is possible to be stably dispersed in the pH range of 6.9–11.6. The coating process made the whiteness of TiO₂ particles decreased slightly but still sufficient (97.3 ±0.1) for application. Furthermore, the properties of the TiO₂ particles coated by P-CVD were compared with the particles coated by traditional wet chemical deposition. It is shown that the P-CVD can produce thinner but denser films with better photoactivity suppression performance. The developed coating process within the rotary reactor was proved practically feasible and convenient for the scale-up production of SiO₂-coated TiO₂ via P-CVD.