Growth Modes Of Carbon Nanofibers Catalyzed By Nickel Nanoparticles On Silicon Substrate

In this paper, nickel nano-islands deposited on monocrystalline silicon substrate were successfully prepared by microwave heating,the carbon nanofibers were prepared using nickel nanoparticles on monocrystalline silicon substrate as catalyzer,carbon nanofibers with nickel coating were synthesized. The paper focuses on three areas:1. Nickel nanoparticles on monocrystalline silicon substrate were prepared using microwave heating in EG system.Monolayer nickel nanoparticles on monocrystalline silicon substrate were successfully synthesized via a simple and fast microwave heating route. The experimental results show that: the size, morphology and distribution of nickel nanoparticles on silicon substrate were impacted by nickel sources, heating way, surfactants, pre-treatment of silicon substrate and reductants. The synthesized products were characterized by the techniques of powder field emission scanning electron microscopy （FE-SEM）, Energy dispersive spectroscopy （EDS）, and X-ray diffraction （XRD）. The results show that when used the hydrazine hydrate as reducing agent, NiCl₂·6H₂O as source of nickel ,the monolayer nickel nano-island on the silicon substrate was prepared by microwave heating and the nickel nano-island was uniform and monolayer, the size of nickel nanoparticles is 30 nm . The size of nickel nanoparticles is about 50 nm in diameter when used NiSO₄·6H₂O as source of nickel, and nickel nanoparticles overlapped.2. Nickel nanoparticles deposited on monocrystalline silicon substrate were successfully prepared by microwave heating method,the carbon nanofibers were prepared in tubular furnace using nickel as catalyst and acetylene as carbon source. The morphology of nickel nanoparticles and carbon nanofibers on silicon substrate was characterized by SEM; the element distribution of nickel nanoparticles on silicon substrate was analyzed by EDS. The growth mode of carbon nanofibers was observed by TEM. The result shows catalyst morphology, reaction temperature, holding time can influence the growth of carbon nanofibers. With the increase of temperature and holding time, the length and diameter of carbon nanofiber increase. Transmission electron microscope photographs shows growth mode of carbon nanofiber catalyzed by nickel nanoparticles on silicon substrate are partly helical symmetric growth and partly linear growth. The HR-TEM result shows carbon nanofiber growth along the （111） crystal plane of nickel nanoparticles is linear growth and growth along the （200） crystal plane of nickel nanoparticles is helical symmetric growth.3. The carbon nanofibers are coated by magnetic nickel nanoparticles via a microwave heating method.The carbon nanofibers with nickel coating were prepared by microwave heating. The phase structures and morphologies of the composites were characterized by SEM, TEM and XRD. The results showed that a dense and uniform layer of nickel nanoparticles coated on the carbon fibers with the particle size of 30 nm-100 nm. In the process of attaching nickel nanoparticles to the surfaces of carbon nanofibers, not only functionally pretreating but also sensitization and activation are indispensable. The size of magnetic Ni nanoparticles on the carbon fibers is adjustable by changing the heating time. The carbon nanofibers with nickel coating can be aligned as a long-chain structure by an external parallel magnetic field.