Synthesis of uniform and stable silver nanoparticles by a gold seed-mediated growth approach in a buffer system

Abstract

A seeding growth approach to the preparation of silver nanoparticles with a controllable size was developed. It contained a two-step reaction: the first step was gold seed clusters quickly generated by a chemical reaction using sodium borohydride as a reducing reagent; the second one was controllable silver nanoparticles were grown at the mild condition by using the mixed reducing reagents (hydroxylamine hydrochloride and sodium hydroxide) to form a buffer system. The gold core was beneficial for the crystalline of silver cations to form the nanoparticles and the buffer system which was composed of hydroxylamine hydrochloride and sodium hydroxide, and was helpful for controlling the size and shape of the as-prepared silver nanoparticles. These as-prepared nanoparticles were characterised by X-ray powder diffraction, UV-Vis spectroscopy (UV-Vis) and transmission electron microscopy along with energy dispersive X-ray spectroscopy. The results indicated that the obtained silver nanoparticles are highly crystallised with an average diameter around 10 nm. The content of gold seeds and the mild reaction rate controlled by the buffer system were considered to be key factors in the control of silver nanoparticles’ morphology and size. A possible mechanism of the silver nanoparticles formed was also proposed.

Keywords:

• gold seeds
• seed-mediated growth
• hydroxylamine hydrochloride
• buffer system
• silver nanoparticles

Acknowledgements

This work was supported by Natural Science Foundation of China (Grants Nos. 51102251 and 31170964), Ningbo Science and Technology Bureau (Grants Nos 2009B21005, 2010A610159 and 2011C50009), Postdoctoral Science Foundation of China (Grant No. 20100480072), Hundred Talents and Academy-Locality Cooperation Programs of Chinese Academy of Sciences, Zhejiang Provincial Natural Science Foundation of China (Grant No. R5110230) and the CAS/SAFEA International Partnership Program for Creative Research Teams.