Synthesis of bimetallic Au-Ag alloyed mesocomposites and their catalytic activity for the reduction of nitroaromatics

Abstract

Homogeneously dispersed Au-Ag alloyed nanostructures varying from spherical (6–8 nm) to rod shape (aspect ratio ∼15–20 nm) were synthesized within the channels of amine modified mesoporous SBA-15 using post modification. Formation of alloy nanostructures for varying Au-Ag loadings have been supported by XPS and elemental mapping studies. Furthermore, changes in the surface/electronic properties of mesocomposites as a function of increased bimetallic Au:Ag loading have been elucidated with the help of XRD, BET, TEM and XPS studies respectively. It was found that synergism owing to electronic interplay between Au and Ag species concurrently improved the catalytic activity of bimetallic nanocomposites. Among the various monometallic and bimetallic mesocomposites, Au-Ag (5:1)/m-SBA-15 nanocomposites exhibited the best catalytic activity (k = 2.12 × 10−2 min−1 and 3.99 × 10−2 min−1) for the selective reduction of nitrobenzene to aniline and p-nitroacetophenone to p-aminoacetophenone respectively.