TIUNOV Ivan Gubkin Russian State University of Oil and Gas

Synthesis of Monodisperse Gold and Gold-Silver Core-Shell Spherical Nanoparticles

Co-authors Maksim GORBACHEVSKII, Dmitry KOPITSYN, Andrei NOVIKOV

Synthesis of metal nanoparticles is a rapidly expanding area of research. However, only few among the many papers on this topic are dedicated to the synthesis of monodisperse and non-aggregated nanoparticles, which is crucial to their further reliable and reproducible usage. In our work, we synthesized monodisperse spherical gold nanoparticles in the size range from 20 to 150 nm, and the gold-silver core-shell nanoparticles in the size range from 60 to 220 nm. We used modified step-by-step method for the synthesis of gold nanoparticles after Bastus et al. [1], which is suitable for the preparation of monodisperse gold sols providing thorough temperature control of the reaction mixture. The monodisperse gold nanoparticles obtained by this method were used as cores in the preparation of the gold-silver core-shell nanoparticles. Size and shape of the synthesized core-shell nanoparticles can be controlled by core nanoparticles concentration, core nanoparticles size, and Ag/Au molar ratio. Varying these factors, one can easily obtained gold-silver core-shell nanoparticles in the size range from 60 to 220 nm with the defined core-shell ratio. The nanoparticles were characterized by UV-Vis spectroscopy, dynamic light scattering (DLS) and transmission electron microscopy (TEM). Gold-silver core-shell nanoparticles were compared to random silver sols in surface-enhanced Raman spectroscopy (SERS) experiments and showed enhancement factors higher than Lee-Meisel [2] and Leopold-Lendl [3] sols. ACKNOWLEDGEMENTS This work is supported by Ministry of Education and Science of the Russian Federation (Target funding, project 16.1812.2014/K). The authors are grateful to Maksim Bardin for the TEM micrographs.