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

Ag-SiO2 nanocomposites (NCs) with plum-pudding structure have been synthesized using a facile reverse micelle method. The as-synthesized Ag-SiO2 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 similar to 2 nm are well dispersed in each SiO2 nanosphere (28 nm). In comparison with free Ag NPs and SiO2 supported Ag NPs, the Ag-SiO2 NCs exhibited a better catalytic activity for the reduction of 4-nitrophenol with a turnover frequency of 489 h(-1) at room temperature. Ag-SiO2 NCs also displayed a superior catalytic activity for hydrogenation of 2-NP and 3-NP. The activation energy of Ag-SiO2 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. (C) 2015 Elsevier Ltd and Techna Group S.r.l. All rights reserved.