Synthesis and characterization of vapor-grown Si/CNF and Si/PC/CNF composites based on Co–Cu catalysts

We report a study on the synthesis and structural characteristics of Si/carbon nanofiber (CNF) and Si/PC/CNF composites. CNFs were synthesized by the chemical vapor deposition using Co and Cu catalysts at a Co:Cu ratio of 6:4. This study focused on the fabrication processes of Si/PC/CNF composites to confirm the contact of Si particles with CNFs. The CNF composites on Si particles were prepared on the basis of the following two processes—Sample 1: CNFs were grown on a simple mechanical mixture of Si particles and catalysts; and Sample 2: CNFs were grown on the surface of pyrolytic carbon-coated Si particles. The morphology and composition of the Si/CNF composites were analyzed by scanning electron microscope and energy dispersive spectroscopy measurements. Physical properties were investigated using X-ray diffraction, Raman, X-ray photoelectron spectroscopy, and thermogravimetric analysis, and the specific surface area was measured by Brunauer, Emmett and Teller. Consequently, pyrolytic carbon coating on the surface of Si particles showed the ability to increase the contact of CNFs to the silicon particles. The resulting pyrolytic carbon-coated Si/CNF (Si/PC/CNF) composite also demonstrated better crystallizability compared with the Si/CNF composite prepared through the first method