Formation mechanism of TiO2 nanoparticles in H2O-assisted atmospheric pressure CVS process

Atmospheric Pressure Chemical Vapor Synthesis (APCVS) route was used for the synthesis of titania (TiO2) nanoparticles. The mechanism of nanoparticles formation were investigated by transmission electron microscopy (TEM), X-ray diffraction analysis, nitrogen adsorption technique (BET) and TG–DTA results for as-synthesized powders. The effect of precursor temperature, H2O effect and effective reaction (ER) zone temperature on the phase structure, nanoparticle size, agglomeration, coagulation, coalescence and nanoparticle morphology were also studied. Also, the effect of thermal velocity on the rate of powder formation, coagulation and coalescence of nanoparticles were discussed theoretically and experimentally. With introducing H2O, the appropriate rate of powder formation increased and size, coalescence and coagulation of nanoparticles decreased, significantly. Also, by using H2O vapor, the crystallinity of nanoparticles sharply increased. The minimum temperature for the synthesis of full anatase phase in atmospheric pressure was obtained to be 700 °C. With increasing precursor temperature, thermal velocity and the rate of powder formation increased. Also, no phase transformation was observed but size, coagulation, coalescence and agglomeration of titania nanoparticles increased whereas the morphology of nanoparticles was similar.

Formation mechanism of anatase phase nanostructure titania powders synthesized by H2O-assisted Atmospheric Pressure Chemical Vapor Synthesis (APCVS) process was studied. As shown in the TEM pictures by introducing water vapor to the reactor, twenty-nanometer dramatic decline in the average size of nanoparticles was observed, coagulation and coalescence of nanoparticles decreased, production rate increased and more nanoparticles with uniform size distribution were obtained.Figure optionsDownload as PowerPoint slideResearch Highlights
► Titania nanoparticles were synthesized in Atmospheric Pressure by (APCVS) route.
► Precursor temperature has significant effect on coagulation of nanoparticles.
► Thermal velocity effect on nanoparticles characteristics was studied.
► With introducing H2O vapor, the average size of nanoparticles decreased, significantly.