Direct growth of carbon nanotubes on metallic substrate with nickel film catalyst using domestic microwave oven

• Main Author: Nguyen, Anh Tuan
• Format: text
• Language: English
• Published: Animo Repository 2009
• Online Access: https://animorepository.dlsu.edu.ph/etd_masteral/3809
• Institution: De La Salle University

Carbon nanotubes (CNTs) are allotropes of carbon with cylindrical nanostructure. Carbon nanotubes have high electron emissions at low voltage due to their high aspect ratio and small tip curvature. Due to this excellent property, carbon nanotubes have been regarded as the most efficient material for electronic devices, such as field emission emitters, electrodes and sensors. In such applications, the growth of carbon nanotubes on the metallic surface and the synthesis at low temperature (below 550oC) is of great importance. The synthesis of CNTs directly on metallic substrate greatly simplifies the preparation of cold cathodes and fulfills the requirement of substrate electroconductivity. In this study, a simple method to produce carbon nanotubes at low temperature (below 500oC) and low vacuum (260 Torr) was developed. Domestic microwave oven with power of 850W was used as energy source. The microwave with electromagnetic wave frequency at 2.4 gigahertz produced by the magnetron of domestic microwave oven caused the production of plasma by a mixture of gases under vacuum condition. The plasma produced enhanced chemical vapor deposition forming carbon nanotubes on the substrate surface coated with catalyst. The catalyst for the growth of CNTs was nickel thin film coated on metallic substrate by electroplating. Acetylene was employed as carbon source in N2/H2 environment. Experiments investigated the effect of plating time, run time, total flowrate and proportion of gas mixture to different properties of product. The morphology of catalyst and product was observed using SEM micrographs. The presence of carbon nanotubes in product was studied using TEM, SEM, FESEM, XRD, BET analysis and the results of these analyses confirmed that CNTs was successfully synthesized. Statistical analysis on the experimental data showed that plating time had a positive effect on carbon nanotubes diameter; run time had a negative effect on yield; total flowrate had a positive effect on CNTs diameter but a De La Salle University iii negative effect on carbon deposited yield; acetylene fraction had a positive effect on CNTs diameter. The experiments showed that the best condition produced 15mg of good quality carbon nanotubes with 50nm diameter and 1.5µm length. This was produced at 500oC, in a 10- minutes run with 1 minute plating time. The optimal flowrates were 150ml/min N2, 15ml/min C2H2, and 35ml/min H2.