Materials Synthesis from Atoms to Systems
Condensed phase growth of nanooysters from Fe-decorated single-wall carbon nanohornsJanuary 03, 2013
The process by which curved nanocones of carbon become encapsulated to form a new hybrid “nanooyster” material (inset) is shown through snapshots of QM/MD simulations. Background is an aberration-corrected, atomic resolution, Z-STEM image of single wall carbon nanohorns and unconverted graphene flakes which served as the feedstock in the process.
New hybrid "nanooysters" consisting of encapsulated metal nanoparticles inside hollow carbon shells were synthesized by transforming single-wall carbon nanohorns with reactive metals in a rapid, high-temperature annealing process. This demonstration confirms that condensed phase processes can efficiently convert solid carbon into new nanostructures, such as nanooysters, and points the way to the creation of new forms of encapsulated metallic quantum dots within environmentally-compatible carbon shells for novel magnetic, optical, and biological applications.
Unraveling the atomistic mechanisms by which nanoscale metal and carbon “building blocks” interact to form nanooysters required a novel “nano-enabled materials design” approach, involving a combination of theory, synthesis, and characterization. Hollow single-wall carbon nanohorns were first synthesized in a laser vaporization process from pure carbon. The nanohorns were decorated with iron nanoparticles and then rapidly heat-treated with a laser to form the nanooysters. Atomic-resolution electron microscopy provided unprecedented characterization of the nanomaterials. Density functional theory-based calculations showed the mechanism by which metal nanoparticles can assist edge coalescence in the nanooyster shell to form a hollow structure.
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K. R. S. Chandrakumar, Jason D. Readle, Chris Rouleau, Alex Puretzky, David B. Geohegan, Karren More, Veena Krishnan, Mengkun Tian, Gerd Duscher, Bobby G. Sumpter, Stephan Irle, and Keiji Morokuma, “High-temperature transformation of Fe-decorated single-wall carbon nanohorns to nanooysters: a combined experimental and theoretical study,” Nanoscale DOI: 10.1039/c2nr31788e