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Silver nanoparticles and nanowires can be efficiently synthesized in high yield using the polyol synthesis method. However, there are many open questions regarding the mechanisms involved, and how the size and morphology can be effectively controlled. In this work, silver nanoparticles were characterized during and after the synthesis procedure. In the early stages, crystalline silver-silver chloride nanoparticles (Ag-AgCl NPs) were the most commonly observed particles. As the reaction progressed, the fraction of Ag-AgCl NPs decreased while the fraction of isolated silver nanoparticles (Ag NPs) increased. We hypothesize that the AgCl in Ag-AgCl NPs dissolves as Ag(I) into the solution and is then reduced to Ag(0), leaving the Ag portion as isolated Ag NPs with similar particle size, morphology, and microstructures. These Ag NPs accounted for the majority of the final product.

Potentiometric sensors, such as polymeric membrane, ion-selective electrodes (ISEs), have been used in the past to monitor a variety of chemical processes. However, the use of these sensors has traditionally been limited to aqueous solutions and moderate temperatures. Here we present an ISE with a high-capacity ion-exchange sensing membrane for measurements of nitrate and nitrite in the organic solvent propylene glycol at 150 °C. It is capable of continuously measuring under these conditions for over 180 h. We demonstrate the usefulness of this sensor by in situmonitoring of anion concentrations during the synthesis of copper and silver nanoparticles in propylene glycol using the polyol method. Ion chromatography and a colorimetric method were used to independently confirm anion concentrations measured in situ. In doing so, it was shown that in this reaction the co-ion nitrate is reduced to nitrite.