Hexadecylamine capped silver and gold nanoparticles: Comparative study on formation and self-organization

Synthesis of silver and gold nanomaterials in a two-phase system at 30 degrees C using hexadecylamine as both reducing as well as capping agent is discussed. Low amine to metal ratio (1.5) was maintained to understand the effect of amine in the growth and stabilization of nanoparticles. Nanomaterials formation was monitored and characterized by XRD, UV-vis spectroscopy, HRTEM and FT-IR. Formation of silver nanoparticles and subsequent self-organization to form elongated structure was conformed by UV-vis spectra and TEM study. TEM image also supports the formation of elongated structure due to the self-organization of nanoparticles in a secondary process. However, no elongated structure is noticed in case of gold. Gold particles of 4-5 nm size are found to aggregates to bigger particles of average size of 12 nm through Ostwald ripening process. FT-IR spectra indicate the formation of aliphatic nitriles during silver and gold reduction process. This study indicates that it is difficult to stabilize the smaller nanoparticles after formation with amine to metal ratio of 1.5. (C) 2010 Elsevier B.V. All rights reserved.