Solar photocatalytic and electrokinetic studies of TiO₂/Ag nanoparticle suspensions

Composites of TiO₂ and Ag nanoparticles were used to study photodegradation of aqueous Rhodamine B under natural sunlight exposure. The addition of Ag powder resulted in a ~45% increase of the photocatalytic activity of TiO₂ after 30min, which is attributed to the suppression of the photo-generated electron-hole pair recombination. Electrokinetic studies on TiO₂, Ag, and TiO₂/Ag aqueous solutions address the question of how the electron transfer occurs. It was found that the TiO₂ and TiO₂/Ag zeta potential versus pH behavior is virtually identical which suggests that the Ag particles are encapsulated by the TiO₂ particles, allowing the electron transfer across the 'static' semiconductor-metal interface.