la0632070_si_001.pdf (398.18 kB)
Cation Exchange: A Simple and Versatile Route to Inorganic Colloidal Spheres with the Same Size but Different Compositions and Properties
journal contribution
posted on 2007-03-13, 00:00 authored by Pedro H. C. Camargo, Young Hwan Lee, Unyong Jeong, Zhiqing Zou, Younan XiaThis paper describes a cation exchange approach to the synthesis of metal chalcogenide core−shell particles with
the same size but a number of different compositions. This method begins with the preparation of colloidal spheres
of amorphous Se (a-Se), followed by their reaction with Ag atoms to form Se@Ag2Se spheres. These core−shell
spheres are then converted into Se@MSe (M = Zn, Cd, and Pb) via cation exchange with Zn2+, Cd2+, and Pb2+. All
the colloidal spheres prepared using this method are monodispersed in size and characterized by a spherical shape
and a smooth surface. Starting from the same batch of Se@Ag2Se, the resultant Se@MSe samples were essentially
the same in size. Furthermore, these core−shell colloidal spheres can be easily made superparamagnetic by incorporating
Fe3O4 nanoparticles into the a-Se cores. This synthetic approach provides a simple and versatile route to magnetoactive
core−shell spheres with the same size but a range of different compositions. This study also implies that it is feasible
to further increase the diversity of cations that can be used in the cation exchange of a colloidal system to produce
multifunctional core−shell spheres with a variety of properties.