One-step fabrication and field emission properties of petal-like carbon nanotubes

Abstract

We have used bias-assisted microwave plasma chemical vapor deposition to synthesize (i) carbon nanotubes (CNTs) possessing a graphitic carbon nanoflake (CNF) morphology, (ii) CNF spheres, and (iii) a pure carbon nanoflake film (CNFF) on stainless-steel substrates. We employed CH(4) and CO(2) as the precursors to these carbon nanomaterials(CNMs); the use of CO(2) aided the destruction of the CNT surfaces and reduced the growth temperature range to 380-450 degrees C at 300 W, as a result of the presence of oxygen-based species in the plasma. Applying an external bias of - 150 V led to the growth of CNTs possessing specifically oriented graphitic CNFs. We used scanning electron microscopy and high-resolution transmission electron microscopy to observe the morphologies and graphitic structures of these CNMs. Field emission measurements of a CNT/CNF-coated electrode revealed that the turn-on field was ca. 2.73 V/mu m. (c) 2008 Elsevier B.V. All rights reserved.