Synthesis of few-walled carbon nanotube–Rh nanoparticles by arc discharge: Effect of selective oxidation

Highly crystalline rhodium (Rh) nanoparticles supported on carbon nanotubes were prepared by selective oxidation method. Carbon nanotubes and FeRh nanoparticles were simultaneously generated in hydrogen arc plasma. The as-grown nanomaterials can be purified by heat treatment in open air and by soaking in HCl. X-ray diffraction and selected area electron diffraction results reveal that as-grown FeRh nanoparticles have a typical chemical CsCl-type structure which can be transformed into a face-centered cubic structure by thermal annealing in the purification process. The purification process is selective toward the removal of the amorphous carbon coating the nanoparticles, and transforms Fe to Fe2O3. Fe2O3 can be easily dissolved in hydrochloric acid, leaving carbon nanotubes–Rh nanoparticles. Rh nanoparticles with diameters of 2–60 nm are deposited uniformly on the surface of the carbon nanotube bundles. This simple and selective chemistry offers a new process for synthesizing and controlling Fe content in carbon nanotube–FeRh nanoparticles.