Field Emission Studies of Carbon Nanocoils Fabricated by Au-K Cooperative Bicatalytic Decomposition of Acetylene

• Main Authors: Tsou, Tsung-Yu, 鄒宗育
• Other Authors: Chiu, Hsin-Tien
• Format: Others
• Language: en_US
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/29683506772835251887

碩士 === 國立交通大學 === 應用化學系碩博士班 === 99 === We demonstrated that the growths of carbon nanocoils (CNCs) via chemical vapor deposition (CVD) using Au and K metals as the catalysts to assist the thermal decomposition of acetylene. Uniformly shaped CNCs, identified as amorphous coiled carbon fibers by scanning electron microscope (SEM) and transmission electron microscopy (TEM), were grown at proper combination of reactant parameters. A metallic Au nanoparticles (NPs), was determined by energy dispersion X-ray spectroscopy (EDX) and electron diffraction (ED), located at the tip of each CNC, suggesting that a tip-growth mechanism involving Au as the nucleation site was in operation. The K assisted the decomposition of C2H2 by lowering the reaction temperature. We suggest that in the reaction, acetylide and hydride intermediates were formed. Further decomposition of the acetylide intermediate deposited carbon solid for the CNC growths. Effect of varying the reaction conditions on the CNC growths was discussed. An 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 (Eto) of 3.78 V m-1 and a field enhancement factor of 1852. In addition, the current density (J) was as high as 43 mA cm-2 at 6.87 V m-1. The results suggest that the CNCs could be promising candidates for field emission device applications.