Nanocoating zinc alkoxide (zincone) hybrid polymer films on particles using a fluidized bed reactor

Abstract

Ultrathin zinc alkoxide (zincone) hybrid polymer films were coated on large quantities of primary titania nanoparticles using molecular layer deposition (MLD) in a fluidized bed reactor. Diethyl zincand ethylene glycol were used as reactants at a reaction temperature of 80 or 120 °C. The composition and conformal zincone films were confirmed by x-ray photoelectron spectroscopy and TEM, respectively. The growth rate was higher at a lower reaction temperature. Primary nanoparticles were coated individually despite their strong tendency to aggregate during fluidization. Porous zinc oxide was formed by the oxidation of the hybrid zincone films in air at 400 °C. The surface area of the porous film itself was ∼40 m2/g for the MLD films after oxidation at 250 °C, and 31 m2/g for the films after oxidation at 400 °C. Methylene blue oxidation tests indicated that the zincone MLD film can reduce the photoactivity of TiO2 particles, but the passivation effect of the aged zincone films decreased due to the decomposition of zincone in the presence of water at room temperature to form a more stable composite containing zinc. The passivation effect of the oxidized zincone films further decreased due to the nonuniformity of the zinc oxide films after crystallization during the oxidation process.