Epitaxial growth of Ag-Cu bimetallic nanoparticles via thermal evaporation deposition

The epitaxial growth of silver on copper benefits carriers' transport across interfaces and is thus important for opto-electronic applications and catalysis. Cu-Ag bimetallic nanoparticles have long been fabricated using chemical methods. The epitaxial growth of silver on copper has been rarely reported. In this study, we demonstrate the fabrication of Cu-Ag bimetallic nanoparticle with a configuration of silver epitaxial growth on copper via thermal evaporation deposition in vacuum, in which not only the oxidation of copper is reduced but also contamination is avoided. Meanwhile, a core-shell-like bimetallic nanoparticle with a copper core and a silver shell is also fabricated. The configurations of the two kinds of Cu-Ag bimetallic nanoparticles were explored by analyzing the changes of the X-ray photoelectron spectra, high resolution transmission electron microscopy images, diffraction rings, and glancing angle X-ray diffraction patterns with the increasing amount of silver and copper. A model of lattice matching between silver on copper was also established for the epitaxial Cu-Ag bimetallic nanoparticle. The layered epitaxial bimetallic nanoparticle show strong anti-oxidation effect and obvious localized surface plasmon resonance damping of Ag nanoparticles, suitable for applications requiring anti-oxidation and low absorbance.