Photocatalytic Synthesis of Gold Nanoparticles Using TiO2 Nanorods: A Mechanistic Investigation
Herein, we investigate the mechanism of photocatalytic synthesis of noble metal nanoparticles by reductive photoelectrons generated from semiconductors. To slow down the reaction rate for real-time mechanism study, the oleic acid-capped TiO2 nanorods served as photocatalysts, chloroauric acid dissolved in oleylamine acted as the gold precursor. Based on the experimental results from the in-situ absorption spectrum and corresponding TEM image, we could clarify the photoreduction mechanism: the TiO2 nanorods generate electrons under UV irradiation and provide catalytic centers for the nucleation of gold nanoparticle. Subsequently, the seeded growth of Au nanoparticles is mainly assisted by TiO2 nanorods with continuous reduction of gold precursor. Interestingly, the separation of Au nanoparticles from TiO2 nanorods could be clearly observed. This proposed reaction mechanism may become a convenient understanding of photocatalytic synthesis of noble metal nanoparticles by semiconductors.