A practical route to the production of carbon nanocages

Carbon-coated iron nanoparticles with diameters ranging from 5 to 50 nm and a few layers of graphitic shells have been synthesized in a mass scale by laser-induction complex heating evaporation. Through the studies on the dissolution behavior of the inner iron cores under the treatments of HCl and HNO3 acids at different conditions, a practical route with the combined treatments of HNO3 and HCl acids has been optimized to produce carbon nanocages. The nanocages thus obtained have some channels and are full of defects in the shells, as characterized by high-resolution transmission electron microscopy and Raman spectroscopy. Similar treatments should also be applicable to some other carbon-coated metal nanoparticles, e.g., Ni-C and Co-C, for the same purpose.