| 초록 |
A simple, environmentally benign green synthetic route was developed for preparing uniform silver nanoparticles with small particle sizes of less than 10 nm at ultra-high concentrations, in which ascorbic acid was used to reduce silver nitrate to silver nanoparticles in the presence of polyethyleneimine (PEI) as a stabilizer. The synthesized silver nanoparticles were characterized using UV-Vis spectroscopy, infrared spectroscopy (FTIR), powder X-ray diffraction (XRD) and transmission electron microscopy (TEM). The highly concentrated (above 200 g L-1) predominantly spherical mono dispersed 8.2 ± 1.6 nm sized silver nanoparticles were obtained for the first time using PEI and ascorbic acid in just 8 min at 90 oC, at least 10 - 250 fold more than the previous reported methods. The catalytic activity of silver nanoparticles was also explored in the catalytic reduction of 4-nitrophenol to 4-aminophenol by NaBH4. The catalytic results indicated the rate constant (k) was 1.37 × 10-3 s-1, and activity parameter κ (where, κ= k/m), was 1142 s-1 g-1 (m = 1.2 × 10-6 g), which is quite higher than the previously reported values. |
