Industrial & Engineering Chemistry Research, Vol.49, No.8, 3654-3662, 2010
Self-Cleaning Films with High Transparency Based on TiO2 Nanoparticles Synthesized via Flame Combustion
Self-cleaning transparent nanoporous films with high photocatalytic properties were obtained based on the self-assembly of TiO2 nanoparticles synthesized by H-2/O-2 combustion flames. Films were prepared from multilayer deposition of poly(sodium 4-styrenesullonate)-treated TiO2 nanoparticles and SiO2 nanoparticles with electrostatic interaction by the adsorption of positively charged poly(diallyldimethylammonium chloride) via layer-by-layer assembly processes. The assembly conditions, such as the pH and concentration of a nanoparticle suspension that cause variation of the surface charge densities, were found to strongly affect the thickness and morphology of multilayer films. TiO2/SiO2 coatings assembled with 10 cycles reach effective photocatalysis with a maximum transmittance of 99.3% as well as a water droplet spreading time as short as 0.29 s. The photodegradation kinetics showed that multilayer films fabricated with 10 cycles are 4 times more active than films assembled with 5 cycles, indicating that flame-synthesized TiO2 with well crystallinity can be used to fabricate high transparent self-cleaning films at suitable assembly conditions. The photocatalytic degradation kinetics dominated by control of the number of assembled cycles was also discussed.