• Groiss, Heiko
• Dippel, Ann-Christin
• Kriegner, Dominik
• Heiss, Wolfgang
• Meffert, Matthias
• Walter, Peter
• Yarema, Maksym
• Stangl, Julian
• Sytnyk, Mykhailo
• Grafeneder, Wolfgang
• Gerthsen, Dagmar

Abstract

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/SnO$_2$ is treated by Ag$^+$, Pt$^{2+}$, Pt$^{4+}$, and Pd$^{2+}$. The conversion dynamics is monitored by in situ synchrotron X-ray diffraction. The Ag+ treatment converts the Sn cores to the intermetallic Ag$_x$Sn (x ∼ 4) phase, by changing the core’s crystal structure. For the analogous treatment by Pt$^{2+}$, Pt$^{4+}$, and Pd$^{2+}$, such a galvanic exchange is not observed. This different behavior is caused by the semipermeability of the naturally formed SnO$_2$ shell, which allows diffusion of Ag$^+$ but protects the nanocrystal cores from oxidation by Pt and Pd ions.

Topics

• nanoparticle
• impedance spectroscopy
• phase
• x-ray diffraction
• intermetallic