Catalytic activity of silver nanoparticles anchored on layered double hydroxides and hydroxyapatite

Abstract

Silver nanoparticles (AgNPs) embedded on solid supports are promising catalysts due to their high reactivity, stability and selectivity. Herein, we report a facile, efficient and low-cost strategy to anchor AgNPs on layered double hydroxides (LDH) and hydroxyapatite (Hap). The abundant surface hydroxyl groups of Hap and LDH were exploited to form hydrogen bonds with carboxylate-capped AgNPs by simply mixing the preformed substrates and silver suspensions. Spectroscopic and electron microscopic characterization studies revealed the highly dispersed AgNPs on both solid supports. The silver contents in the products obtained were found to depend on the availability of hydroxyl groups in the solid supports. The highest silver content of 6.25 ± 0.15 wt% was achieved when using reconstructed LDH, previously calcined at 450 °C, as a substrate. The rate constants of the 4-nitrophenol reduction catalyzed by Ag/LDH (4 – 6 wt% Ag) were about 2.5 times higher than that of pure AgNPs. The catalytic activity of materials improved with the increase of silver content and reached the maximum at 4 wt% Ag. In addition, the decrease in particle size of AgNPs was another factor to enhance the catalytic activity.