Preparation Of Silver Nanoparticles And Analysis Of Their Shape-Effected Factors

Nano-materials are important research areas of modern science and technology. Inthe21th century, silver nanoparticles have caused widespread concerns around theworld, due to their promising applications in optoelectronics, catalysis, sensing,medicine, and so forth. Recently, we have committed to the following aspects:1) tostudy the growth mechanism of silver nanoparticles and to control and regulate theirmorphologies;2) to develop green preparation methods with non-toxic, environmentalfriendly and renewable reagents;3) to prepare shape-controlled silver colloids withdifferent concentrations in organic media.In view of the above aspects, we developed two systems in aqueous phase andorganic phase respectively through chemical reduction method. And the productswere characterized by UV-vis, Zetasizer, TEM, SEM.1H NMR and FT-IR wereperformed to analyze the formation of silver-amine complex.Nearly monodispersed, water-soluble starch capped silver decahedrons wereprepared in aqueous phase using pyruvate as a bio-friendly reductant without anysynthetic additives. To determine the optimal conditions for preparing monodispersedsilver nanoparticles, we regulated the amount of starch and sodium pyruvate, thealkalinity, reaction temperature and reaction time. Given to the special structure ofdecahedron and its growth mechanism, we introduced sodium iodide as ashape-directing agent to modulate the anisotropic growth. As a result, nanorods andtriangles/truncated triangles were obtained.The preparation of silver nanoparticles in organic media is considered to be a wayto achieve high concentration. Silver nanoparticles were first generated by reductionof silver-amine complex with isobutyraldehyde (IBD) in the presence of polyvinylbutyral (PVB) in alcohol solution. A large number of experiments were conductedwhile varying silver amine solution, alcohol solvents, and reaction time.Tert-butanol-DEAm system is confirmed to be the optimal protocol to prepare highconcentration silver nanoparticles (0.24M/L), in which stable and high yield (>80%)silver nanoparticles with average sizes of~50nm are obtained. We also studied andcharacterized the silver nanoparticles prepared in low concentration (20mM/L). It was found that compared with high concentration, various morphologies generated,including sphere, triangles/truncated triangles.