Hydrothermal synthesis of silver nanoparticles by sodium alginate and their applications in surface-enhanced Raman scattering and catalysis

Various methods have been reported for the synthesis of Ag nanoparticles (NPs) by reduction of AgNO3 with a chemical reducing agent. However, many of them pose potential environmental and biological risks. Herein, we demonstrate for the first time that Ag NPs can be synthesized using sodium alginate (NaAlg) as both reducing and stabilizing agents by a simple and effective green hydrothermal strategy. By controlling the temperature and time of reaction, Ag nanospheres and nanoplates can be fabricated. Moreover, the application of an Ag NPs–NaAlg thin film in surface-enhanced Raman scattering of rhodamine 6G is demonstrated. The catalytic efficiency of the as-prepared Ag NPs embedded in calcium alginate beads is evaluated for reaction of 4-nitrophenol reduction to 4-aminophenol in the presence of NaBH4.