Alginate fibers embedded with silver nanoparticles as efficient catalysts for reduction of 4-nitrophenol

Silver nanoparticles (AgNPs) have attracted much attention as promising catalysts in various electron transfer reactions due to their high catalytic efficiency. However, their poor stability results in the decrease of the catalytic efficiency and the poor cycling performance, which have hindered the practical application of AgNPs. In this work, alginate fibers embedded with AgNPs were prepared via in situ reduction of Ag+-alginate fibers in the presence of glucose. Field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM) indicated that spherical AgNPs dispersed on the surface and the interior of the fibers. The alginate fibers could enable AgNPs to be highly stabilized and thus led to the excellent reusability as heterogeneous catalysts for the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) in aqueous media. The catalytic results indicated that 4-NP could be reduced completely within 15 min. Moreover, the catalyst was easily recovered and reused for at least ten cycles in the reduction reactions, confirming its excellent stability. Most importantly, compared to the conventional powdery catalysts, the fiber catalyst could be handled much more conveniently for re-usage owing to its easily separation.