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◦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 selforganization
of nanoparticles in a secondary process. However, no elongated structure is noticed in case
of gold. Gold particles of 4–5nm size are found to aggregates to bigger particles of average size of 12nm
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.