Abstrakt
While galvanic exchange is commonly applied to metallic nanoparticles, recently its applicability was expanded to metal-oxides. Here the galvanic exchange is studied in metal/metal-oxide core/shell nanocrystals.
In particular Sn/SnO2 is treated by Ag+, Pt2+, Pt4+, and Pd2+. The conversion dynamics is monitored by in situ synchrotron X-ray diffraction.
The Ag+ treatment converts the Sn cores to the intermetallic AgxSn (x similar to 4) phase, by changing the core's crystal structure. For the analogous treatment by Pt2+, Pt4+, and Pd2+, such a galvanic exchange is not observed.
This different behavior is caused by the semipermeability of the naturally formed SnO2 shell; which allows diffusion of Ag+ but protects the nanocrystal cores from oxidation by Pt and Pd ions.