Extremely Active Pd@pSiO 2 Yolk–Shell Nanocatalysts for Suzuki Coupling Reactions of Aryl Halides

In the present study, we optimize the yolk–shell nanostructure in a palladium–silica system for the purpose of attaining high activity in Suzuki cross-coupling reactions. Pd@porous SiO 2 (Pd@pSiO 2 ) yolk–shell nanoparticles, bearing tiny palladium cores and highly porous silica hollow shells, were synthesized by direct silica coating and partial etching of the silica layers. High temperature treatment removed all surfactants around the catalyst surface and generated large pores on the silica shells. The resulting Pd@pSiO 2 yolk–shell catalysts exhibited extremely high initial turnover frequency of 78000 h –1, as well as excellent reusability of more than 10 times in a standard Suzuki coupling reaction. The catalysts also catalyzed Suzuki reactions with various substrates including bromo- and chlorobenzene very well.