Nanocrystallinity and the Ordering of Nanoparticles in Two-Dimensional Superlattices: Controlled Formation of Either Core/Shell (Co/CoO) or Hollow CoO Nanocrystals

作者：Yang Zhijie; Lisiecki Isabelle; Walls Michael; Pileni Marie Paule^*

来源：ACS Nano, 2013, 7(2): 1342-1350.

DOI：10.1021/nn304922s

• Co nanoparticles
• nanocrystallinity
• 2D ordering effect
• core/shell structures
• hollow structures
• STEM
• EELS

Here it is demonstrated that the diffusion process of oxygen in Co nanoparticles is controlled by their 2D ordering and crystallinity. The crystallinity of isolated Co nanoparticles deposited on a substrate does not play any role in the oxide formation. When they are self-assembled in 2D superlattices, the oxidation process is slowed and produces either core/shell (Co/CoO) nanoparticles or hollow CoO nanocrystals. This is attributed to the decrease in the oxygen diffusion rate when the nanoparticles are interdigitated. Initially, polycrystalline nanoparticles form core/shell (Co/CoO) structures, while for single-domain hexagonal close-packed Co nanocrystals, the outward diffusion of Co Ions is favored over the inward diffusion of oxygen, producing hollow Co0 single-domain nanocrystals.

• 出版日期2013-2