Synthesis and mechanism study of the highly monodispersed extra-small silver nanoparticles in reverse micelles

Silver nanoparticles (Ag NPs) play a significant role in catalysis, biosensor, antibacterial activity, SERS spectroscopy, and photoelectric materials. These prominent applications are strongly dependent on the size and uniformity of Ag NPs. However, a variety of preparation methods such as electrochemical and green synthesis methods are of difficulties to obtain extra-small and uniform Ag NPs due to complex growth environment, which is prone to render anisotropy of nanoparticles thereby limiting the development of Ag NPs. To address the unmet need, tremendous effort has been made synthesizing extra-small Ag NPs with the outstanding monodispersity and remarkable stability in reverse micelles. The efficient and facile method is established employing a high-performance protective agent, i.e., octadecylamine (ODA) with the average diameter of 3.36  ±  1.0  nm. Moreover, by adjusting octadecylamine concentration, the versatile method has the capability of controlling the size of Ag NPs precisely. In addition, the growth mechanism of Ag NPs based on nucleation theory is described schematically, which is of widespread generality to adapt our method for the preparation of other nanoparticles in the similar system. Overall, the promising strategy to the synthesis of extra-small Ag NPs lays a solid foundation for potential applications in wound healing, health care, medical diagnosis, and environmental remediation.