標題: K and Au Bicatalyst Assisted Growth of Carbon Nanocoils from Acetylene: Effect of Deposition Parameters on Field Emission Properties
作者: Tsou, Tsung-Yu
Lee, Chi-Young
Chiu, Hsin-Tien
應用化學系
Department of Applied Chemistry
關鍵字: carbon nanocoils;Au catalyst;K catalyst;field emission
公開日期: 1-十二月-2012
摘要: We demonstrated the growth of carbon nano-coils (CNCs) via chemical vapor deposition (CVD) using Au and K metals as the catalysts to assist the thermal decomposition of C2H2. Typical CNCs (wire diameter: 50-80 nm, coil diameter: 110-140 nm, pitch: 100-200 nm, tens of micrometers), identified as amorphous coiled carbon fibers by scanning electron microscopy (SEM) and transmission electron microscopy (TEM), were grown at proper combinations of reaction parameters. Au nanoparticles (NPs), identified by energy dispersion X-ray spectroscopy (EDX) and electron diffraction (ED), were located at the tips of the CNCs. The observations suggested that a tip-growth mechanism involving the Au NPs as the nucleation sites was in operation. In the reaction, the liquid-phase K metal assisted the decomposition of C2H2 by lowering the reaction temperature. We propose that acetylide and hydride intermediates were formed in the reaction. Further decomposition of the acetylide intermediates generated solid-phase carbon to grow the CNCs. Effects of varying the reaction conditions on the CNC growth were investigated. On the basis of the results, a Au and K bicatalyst enhanced tip-growth vapor-liquid-solid (VLS) mechanism was proposed to rationalize the CNC formation process. Electron field emission (EFE) characteristics of the CNCs were studied. The best EFE result showed a turn-on field (E-to) of 3.78 V/mu m and a field enhancement factor (beta) of 1852. In addition, the current density (J) was as high as 43 mA/cm(2) at 6.87 V/mu m. The data suggest that the CNCs could be employed for field emission device applications.
URI: http://dx.doi.org/10.1021/am3015372
http://hdl.handle.net/11536/20921
ISSN: 1944-8244
DOI: 10.1021/am3015372
期刊: ACS APPLIED MATERIALS & INTERFACES
Volume: 4
Issue: 12
起始頁: 6505
結束頁: 6511
顯示於類別:期刊論文


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