Reduction process of nickel cations anchored on carbon nanotubes

Multi-walled carbon nanotubes were decorated with nickel cations after nitric acid oxidization and the resultant product was calcined in an inert atmosphere. The samples were characterized by transmission electron microscopy and X-ray diffraction. The nickel oxide nanoparticles were initially dispersed on the external surfaces of carbon nanotubes. Continuous calcination in an inert atmosphere caused the reduction of nickel oxide nanocrystals to metallic nickel nanoparticles, where carbon nanotubes functioned as reducing agent. The metallic nickel nanoparticles were deposited on the surface of nanotubes and they could be used as catalyst in homogeneous or heterogeneous reactions.