Morphology of zigzag carbon nanofibers prepared by catalytic pyrolysis of acetylene using Fe-group containing alloy catalysts

Abstract

The morphologies of the two-dimensional (2D) zigzag carbon nanofibers obtained by the catalytic pyrolysis of acetylene using the Fe-containing catalysts are examined in detail, and the growth mechanism is also discussed. Using the alloy catalyst of Fe-38Cr-4Mn-4Mo at the reaction temperature 750–790 °C, the zigzag carbon nanofibers were formed at a higher content (20–50%) in deposits together with the twisted carbon nanocoils. The morphology of the zigzag carbon nanofibers mainly depended on the catalysts, and carbon nanofibers with various zigzag morphologies were obtained. The growth of large amounts of regular zigzag carbon fibers was observed in the presence of the high Fe-containing alloy catalyst, suggesting that the Fe element plays an important role in the formation of the regular zigzag carbon nanofibers. There is some possibility of masking or deactivating of one crystal face among the three catalyst crystal faces by the Fe element, and thus only two crystal faces are involved in the growth of the 2D-zigzag fibers while the three dimensional-helical/spiral structure of the carbon nanocoils is formed from three crystal faces.