ROMP synthesis of gallol-containing polymer hydrogels for in situ fabrication of AuNPs and AgNPs composites as recyclable catalysts for the degradation of 4-nitrophenol

Abstract

Metal nanoparticle composite hydrogels (MNCHs) have attracted considerable attention in the catalytic field because hydrogels can provide appropriate microenvironment and enable catalysts to be conveniently separated and recycled. Here, a novel and well-defined gallol-functionalized hydrogel Gel-G was synthesized by ring-opening metathesis polymerization (ROMP). The resulting hydrogel Gel-G can be used as template to in situ prepare catalytically active gold nanoparticles hydrogel (AuNPs-Gel-G) and sliver nanoparticles hydrogel (AgNPs-Gel-G) without use of any external reductant based on the strong reducibility and coating property of the gallol moiety. The two MNCHs were well characterized by scanning electron microscope (SEM) and X-ray diffraction (XRD). Both AuNPs-Gel-G and AgNPs-Gel-G exhibited high catalytic activity for the 4-nitrophenol (4-NP) reduction to 4-aminophenol (4-AP), and can be easily separated and reused at least five times.