AAAR 37th Annual Conference October 14 - October 18, 2019 Oregon Convention Center Portland, Oregon, USA
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One-step Gas-phase Synthesis of Core-shell Nanoparticles via Surface Segregation
NAMSOON EOM, Markus Snellman, Martin Ek, Maria Messing, Knut Deppert, Lund University
Abstract Number: 744 Working Group: Nanoparticles and Materials Synthesis
Abstract A great amount of research effort has been devoted to the production of core-shell nanoparticles for applications in various fields including biomedical imaging, catalysis, and plasmonics. Such attention to core-shell nanoparticles arise from the fact that they can exhibit enhanced physical and/or chemical properties. Furthermore, core-shell particles with distinctly new properties compared to those of the constituent materials can be designed by tuning, for example, their size, shell thickness, and structure [1, 2].
Although chemical synthesis techniques are currently the most popular methods for fabricating core-shell nanoparticles, interface and surface contaminations are often an unavoidable issue in the solution-based approaches. Aerosol based methods are cleaner alternatives and have been used to produce core-shell nanoparticles [3-6]. Here we present aerosol core-shell nanoparticles generated via spark discharge generation (SDG) [7]. Cu-Ag core shell nanoparticles were fabricated via surface segregation using SDG accompanied by sintering directly in the gas phase. The surface segregation employed in this method refers to the phenomenon of the enrichment of one component of a mixture in the surface region and is attributed to the interplay between the atomic radii, cohesive energy, and surface energy of the core and shell materials [8].
Depending on the sintering temperature, the SDG-generated nanoparticles form Janus-like or core-shell structures. The morphology, crystallinity, and composition of the SDG-generated bimetallic nanoparticles were investigated by scanning electron microscopy, high-resolution transmission electron microscopy, and energy-dispersive X-ray spectroscopy. Molecular dynamics simulations were carried out to investigate the structural evolution of Cu-Ag nanoparticles during heating and cooling processes corresponding to the sintering. This appealingly simple one-step gas-phase synthesis method presented here can be employed for other bimetallic systems.
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