Abstract
The effect of argon on the growth of carbon nanotubes (CNTs) in anodic aluminum oxide (AAO) pores was investigated. A thin layer of Co was electrodeposited at the bottom of pores. The CNTs were grown using hot filament chemical vapour deposition by decomposing a mixture of C2H2:H-2 on a tungsten filament. Argon was used as diluent to this mixture and its content was varied keeping C2H2:H-2 ratio constant. It was observed that the Ar content affects the growth, density and morphology of the CNTs. Ultra-high resolution field emission microscopic (UHR-FESEM) and transmission electron microscopic (TEM) observation shows fine tubular multi-wall structure with diameter of similar to 20 nm. Two prominent Raman peaks are observed at 1330 cm(-1) (D band) and 1600 cm(-1) (G band). The ratio of peak intensities (I-D/I-G) was decreased from 2.0 to 0.83 with increasing argon content, indicating that the amount of disordered/amorphous carbon decreased with increasing ratio of Ar. Photoelectron spectroscopic results indicated that when the Ar-content is below 70%, the C 1s peak is centered at 284.4 eV and above this, a shift is observed towards a lower binding energy, centered at 283.8 eV. The effect of C-2 dimer as a dominant growth species is discussed.