Precision synthesis and growth kinetics of one-dimensional carbon nanostructures by Co-based catalysts

Abstract

Microstructures of one-dimensional carbon nanomaterials directly govern their properties and applications. Thus, precise structural control remains a focus goal of carbon-nanomaterial research. Transition-metal catalysts induce the growth of one-dimensional carbon nanomaterials via the adsorption and precipitation of carbon atoms. However, how oxygen doping in the catalyst affects the resulting nanostructures remains incompletely understood. In this work, Co-based catalysts were exposed to either a carbon-only or an oxygen-containing atmosphere, leading to the synthesis of two one-dimensional carbon nanomaterials with distinctly different microstructures. Bamboo-like carbon nanotubes (CNTs) were synthesized in the carbon-only atmosphere, whereas solid wire-like carbon nanowires (CNWs) were obtained in the oxygen-containing atmosphere. Compared CNTs and CNWs, the graphite layers within the carbon nanomaterials exhibit different stacking orientations. Energy-dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and selected-area electron diffraction (SAED) were employed to analyze the elemental distribution and crystal structure of the Co-based catalysts. The CoO phase was confirmed to exist within the catalysts of CNWs, which redirected the microstructures of the one-dimensional carbon nanomaterials by modulating the phase stability and lattice parameters. Therefore, this work discovers a new way for altering the microstructure of one-dimensional carbon nanomaterials.