Core-shell Cu-Ag Nanoparticles Produced by Spark Discharge Generation

The synthesis of core@shell nanoparticles has predominantly been carried out by chemical methods or physical deposition of a shell material post-growth onto core particles. By combining immiscible materials that differ in surface energy, we demonstrate the spontaneous atomic rearrangement to monodisperse Cu@Ag core@shell particles directly in the aerosol phase, starting from pure Cu and Ag electrodes with the spark discharge generation (SDG) method. The morphology and crystallinity were investigated by SEM and HRTEM, and the composition was confirmed by STEM EDX, which indicated that the Ag shell acts as an oxidation barrier for the Cu core. The current material system may find applications in antibacterial coatings. The method presented can be extended to other bimetallic systems with applications in catalysis, plasmonics and as seed-particles for nanowire growth. Owing to the simple, zero-waste and continuous production method, SDG is an ideal platform for such nanoparticle generation and investigation.