Quantitatively loaded ultra-small Ag nanoparticles on molecularly imprinted mesoporous silica for highly efficient catalytic reduction process

Noble metal nanoparticles are widely applied in the catalytic reactions with projected superior activity and selectivity. Usually, the surface atomic species function as active sites, and tailoring the size of the nanoparticles can control the catalytic activity of metal nanoparticles. However, it is still of great challenge to synthesize ultra-small metallic nanoparticles owing to the Ostwald ripening. Herein, confinement of molecularly imprinted cavities strategy was utilized to quantitatively load ultra-small Ag nanoparticles in the mesoporous silica matrix. The average particle size of the Ag nanoparticles was calculated to be around 2 nm, and these nanoparticles were uniformly dispersed in the skeleton of silica matrix without blocking the mesopores. The contents of Ag nanoparticles can be accurately adjusted according to the incorporated organosilica in the mesoporous silica matrix. As expected, the supported Ag nanoparticles exhibited highly efficient catalytic performance towards 4-nitrophenol hydrogenation reactions and showed considerable recycling stability without loss of Ag species.