Surface Chemistry and Dispersion Property of TiO 2 Nanoparticles

The effect of a foreign substance, silica (SiO 2 ), on the surface chemistry, chemical reactivity, and dispersibility of titania (TiO 2 ) nanoparticles was investigated. SiO 2 covers 90% of the surface of commercially available TiO 2 nanoparticles and provides higher acidity, which facilitates the absorption of alkaline surfactant, oleylamine, onto TiO 2 nanoparticles, leading to more efficient nanoparticle dispersion. By removing the surface SiO 2 with an acid treatment, the acidity of TiO 2 was highly reduced and became favorable to being adsorbed and dispersed by the acidic surfactant, oleic acid.