Nanotech 2010

Formation mechanism of copper-silver metal nanoparticle encapsulated in carbon shell

H.Y. Kang, H.P. Wang, C.H. Huang, C.K. Tsai
National Cheng Kung University, TW

Keywords: core-shell nanoparticle, copper, SAXS, silver


The formation mechanism of nanosize copper-silver encapsulated in the inert carbon shell (CuAg@C) has been studied by in-situ small angle X-ray scattering (SAXS) spectroscopy. SAXS is a very useful method in studies of electron density distributions of nanoparticles. The in-situ synchrotron SAXS spectra have been determined during the temperature-dependent formation of the nanosize CuAg@C. A detailed structural changes corresponding to the growth of the CuAg nanoparticle during carbonization of Ag+-, Cu2+- and beta-cyclodextrin (beta-CD) complexes at the temperature range of 303-573 K is observed. By controlling the molar ratios of OH on beta-CD to metal (OH/M), the desired size (i.e., ranged from 7 to 40 nm) can be synthesized. Note that a characteristic transition temperature for the growth of the 14 nm CuAg(1:1)@C is found. A rapid growth of the CuAg nanoparticle occurs at 333-533 K. As expected, by TEM, the CuAg@C nanoparticles have a diameter of about 14 nm with the carbon shell thickness of about 3-5 nm.
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