Large-scale microwave CVD system for synthesis of carbon nanotubes

Abstract

Carbon nanotubes (CNTs) are an interesting class of nanostructures which can be thought of as arising from the folding of a layer of graphite (a graphene sheet ) to form a hollow cylinder composed of carbon hexagons. However, practical applications are still limited by the intricate process of synthesis and the inability of present day methods for large scale production of carbon nanotubes. Morevoer high quality nanotubes with functionalization capability with polymers are desired for polymer MEMS, Nanodevices and BioMEMS. In this paper, an innovative CVD approach using microwave energy was developed for large scale production of single wall and multiwall carbon nanotubes (MWNTs). Straight and helical carbon nanotubes were obtained when acetylene decomposed over the cobalt catalyst at 700 o C created by microwave field. The scanning electron microscopy (SEM) of microwave driven MWNTs revealed their homogenous nature. The high resolution electron microscopy (HRTEM) showed typical MWNT has 26 layers. The average diameter of the tubes was observed 20-30 nm. Electron microscope observations showed higher yield of nanotubes obtained from microwave CVD than thermal filament CVD method.