Effects of ferrite catalyst concentration and water vapor on growth of vertically aligned carbon nanotube

Thi Thanh Cao, Van Chuc Nguyen, Thi Thanh Tam Ngo, Trong Lu Le, Thai Loc Nguyen, Dai Lam Tran, Elena D Obraztsova and Ngoc Minh Phan

Abstract

In this study Fe₃O₄ nanoparticles were used as catalysts for the growth of vertically aligned carbon nanotubes (VA-CNTs) by chemical vapor deposition (CVD). The effect of catalyst concentration and water vapor during the CVD process on the properties of the VA-CNTs was investigated. Monodisperse Fe₃O₄ nanoparticles (4.5–9.0 nm diameter) prepared by thermal decomposition of iron acetylacetonate compounds were spin-coated on clean silicon substrates which served as a platform for VA-CNTs growth. The results indicated that the length, density and growth rate of CNTs were strongly affected by the catalyst concentration. CNTs grown at 0.026 g ml⁻¹ Fe₃O₄ catalyst had greater length, density and growth rates than those obtained at 0.01 and 0.033 g ml⁻¹ Fe₃O₄ catalyst. Addition of water during the CVD process had drastically improved CNTs growth. The length and growth rate of obtained CNTs were 40 μm and 1.33 μm min−1, respectively. The results provided insights into the role of Fe₃O₄ catalyst and water vapor during VA-CNTs growth process by CVD method and the obtained information might serve as a starting point for further optimization of VA-CNTs synthesis