Amino-functionalized silica nanoparticles with center-radially hierarchical mesopores as ideal catalyst carriers.

Our previously fabricated amino-functionalized silica nanoparticles (NPs) with center-radially hierarchical mesopores (NH(2)-HMSNs) were purified by a filtration membrane and used as catalyst carriers in the current article. Noble metal NPs (Au, Pd, Pt and Au & Pt) with small sizes (3-8 nm) were successfully immobilized into the NH(2)-HMSNs via the deposition-precipitation method. These noble metal NPs with readily adjusted small sizes have high density and well-dispersed distribution on the surface of large mesopores of NH(2)-HMSNs. Among them, Au-NH(2)-HMSNs were investigated as the composite catalyst in the catalytic reduction of 2-nitroaniline (2-NA) as a model reaction and exhibited excellent catalytic activity and stability. The presence of center-radially large mesopores in the NH(2)-HMSNs may favor the loading of noble metal NPs with high density and well-dispersed distribution on the surface of large mesopores of NH(2)-HMSNs. Metal-NH(2)-HMSNs may be more promising composite catalysts due to their superstructure of center-radially hierarchical mesopores that maybe significantly enhance and harmonize the diffusion of guest molecules of different sizes through the porous matrices. This journal is © The Royal Society of Chemistry 2012