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.