In-situ loading of noble metal nanoparticles on hydroxyl-group-rich titania precursor and their catalytic applications

A novel in-situ route was developed to load well-dispersed palladium (Pd) nanoparticles on the surface of hydroxyl-group-rich titania precursor. Pd nanoparticles are formed by in-situ reduction of Pd(II) by Sn(II); the latter is linked to the surface of TiO₂ precursors through inorganic grafting. The initial Pd nanoparticles then serve as seed for subsequent particle growth and allow us to systematically control the amount and size of the Pd nanoparticles by varying the amount of added PdCl₂. The Pd nanoparticles, with no protection from ligands, are well-dispersed on the TiO₂ precursor surface without aggregation even at a high Pd loading of 22.5 wt %. The method is also extended to introduce other noble metal nanoparticles including Au, Ag, Pt, and their bimetallic nanoparticles onto the TiO₂ precursor surface. The as-obtained TiO₂ precursor-Pd composite is a promising catalyst in nanocatalysis. As an example, the TiO ₂ precursor-Pd shows high catalytic activity for Suzuki cross-coupling reaction and can be recycled multiple times without loss of activity.