Nanocomposite hydrogel as a template for synthesis of mono and bimetallic nanoparticles

Nanocomposite hydrogels (NC gels) with polymer c lay network assemblies are useful in a number of applications because of their unique properties and characteristics. Herein, we describe a distinctive strategy for the preparation of discrete monometallic (Ag, Au, and Pd) and bimetallic (Pt-Pd, Au-Pd) nanoparticles that uses a nanocomposite hydrogel composed of a polymer clay network. Thermoresponsive NC gels were synthesized by the in-situ free-radical polymerization of N-isopropylacrylamide in the presence of clay (synthetic hectorite) nanosheets (CNSs). Since CNSs have strong affinities for metals ions that facilitate the concentration of metal precursors around them, the reduction of metal ions by ascorbic acid in NC gels provides well-dispersed, non-aggregated spherical monometallic and bimetallic nanoparticles (NPs) that are strongly immobilized within the polymer-clay network. The resulting hybrid NP-NC gels, which contain monometallic or bimetallic NPs, exhibit high catalytic activities for the hydrogenation of nitrophenol to aminophenol. The combination of well-defined metal NPs and mechanically tough NC gels opens up new possibilities for the design of environmentally friendly and sustainable functional NP-NC-gel materials.