Abstract

Carbon nanofibers (CNFs) have been synthesized in high yield (>70%) by catalytic chemical vapor deposition (CCVD) on Co/LiF catalyst using acetylene as carbon source. A novel catalyst support (LiF) is reported for the first time as an alternative for large-scale production of carbon nanofibers while purification process of nanofibers is easier. In our experiment, the sealed furnace was heated at700∘Cfor 0.5 hour (the heating rate was10∘C/min) and then cooled to room temperature in the furnace naturally. Catalytic chemical vapor deposition is of interest for fundamental understanding and improvement of commercial synthesis of carbon nanofibers (CNFs). The obtained sample was sequentially washed with ethanol, dilutes acid, and distilled water to remove residual impurities, amorphous carbon materials, and remaining of catalyst, and then dried at110∘Cfor 24 hours. The combined physical characterization through several techniques, such as high-resolution transmission electron microscope (TEM), scanning electron microscope (SEM), thermogarvimetric analysis (TGA), and zeta-sizer and Raman spectroscopy, allows determining the geometric characteristic and the microstructure of individual carbon nanofibers. Catalytic chemical vapor deposition is of interest for fundamental understanding and improvement of commercial synthesis of carbon nanofibers (CNFs). As a matter of fact, the method of CCVD guarantees the production of CNFs for different applications.

Highlights

  • Carbon nanostructures have been intensively investigated due to their unique one-dimensional structure with adjustable electronic conductivity and unusual mechanical strength [1–3]

  • The result indicates that lithium fluoride (LiF) plays an important role in synthesizing carbon nanofibers (CNFs)

  • It is important to mention that the CNFs are grown at the temperature below the melting point of LiF (m.p. = 848.2◦C) by using thermal chemical vapor deposition (CVD)

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Summary

Introduction

Carbon nanostructures have been intensively investigated due to their unique one-dimensional structure with adjustable electronic conductivity and unusual mechanical strength [1–3]. Since their discovery in 1991 [1], carbon nanotubes (CNTs) and carbon nanofibers (CNFs) have attracted a deal of interests due to their own unique characteristics and potential applications such as separation, gas sensing, catalyst support, energy storage, and environmental protection [4–6]. Among many published techniques for the fabrication of carbon nanotubes/nanofibers, catalytic chemical vapor deposition (CCVD), carried out with a small quartz/alumina tube under atmospheric pressure and high gas flow rate, has been found to be the only reliable method that can produce helical nanotubes with fine regular coils. In the normal CCVD process, a high percentage of the gases used (such as C2H2, H2, N2, and Ar) is discharged into the atmosphere without any participation in the chemical reaction [13–24]

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