Ag–SiO2 nanocomposites with plum-pudding structure as catalyst for hydrogenation of 4-nitrophenol

Ag–SiO 2 nanocomposites (NCs) with “plum-pudding” structure have been synthesized using a facile reverse micelle method. The as-synthesized Ag–SiO 2 NCs were calcined at 623   K to remove the surfactants and then characterized by XRD , FE-SEM, TEM, EDX, ICP and N 2 adsorption–desorption. The obtained results demonstrated that many ultrafine Ag nanoparticles (NPs) with size of ~2   nm are well dispersed in each SiO 2 nanosphere (28   nm). In comparison with free Ag NPs and SiO 2 supported Ag NPs, the Ag–SiO 2 NCs exhibited a better catalytic activity for the reduction of 4-nitrophenol with a turnover frequency of 489   h −1 at room temperature. Ag–SiO 2 NCs also displayed a superior catalytic activity for hydrogenation of 2-NP and 3-NP. The activation energy of Ag–SiO 2 NCs was estimated to be about 34.4   kJ   mol −1 , which was lower than most of the reported values for the same reaction using Ag-based catalysts, indicating the superior catalytic performance of these plum-pudding structured catalysts.