Rapid Synthesis of Silver Nanoparticles using a Household Microwave and their Characterization

Here, we report a novel rapid method for Ag nanoparticle (NP) synthesis using a household microwave. In this procedure, Ag NPs were formed from an aqueous solution containing AgNO3 and D-glucose when microwaved for few seconds. The temperature at the end of the microwaving reached merely 80 °C. Neither a capping reagent nor an oxygen-free environment was necessary. A ten-fold molar excess of glucose over AgNO3 produced maximum NPs, which are stable for months in the absence of stabilizing agents. UV/vis spectroscopy of the colloidal mixture showed a broad Plasmon resonance band in the range 380 to 470 nm with a λmax of ~450 nm indicative of metallic Ag NPs. STM and TEM revealed the NPs were mostly oval and the size across ranged from 5 to 50 nm with the most abundant population in the ~25 nm range. Further analysis using HRTEM exhibited the prominent fringes with regular spacing due to Moiré interference. To our knowledge, this is the first report of synthesis of Ag NPs using a household microwave. The method employs a green approach and reduces the synthesis time to minutes suitable for an experiment in undergraduate teaching laboratories. During the rest of the laboratory period, students can be engaged in further in-depth studies of the NPs using UV/vis spectrophotometry and/or scanning tunneling microscoscopy (STM).