A Study on Reaction Mechanism of the Catalytic CVD Synthesis of SWNTs

Abstract

The catalytic reaction mechanism in the growth process of single-walled carbon nanotubes (SWNTs) is considered for carbon monoxide catalytic CVD (COCCVD) and alcohol catalytic CVD (ACCVD) methods. Combinatory CVD experiments were carried out employing a wide variety of catalyst metals, ranging from commonly used transition metals such as Co and Mo to noble metals such as Au and Pt. As a result, we propose that difference in eletronegativity is a key factor to choose a pair of binary catalysts. In the efficient catalyst reaction for a combination of catalyst metals with large electronegativity difference, the metal atom with larger electronegativity functions as a carbon bonding site, and other metal atoms help the dissociation of H2. For the combination of similar electronegativities, the metals have no work-share. Furthermore, catalytic activity of Au and Pt are demonstrated for COCCVD in addition to the previously reported ACCVD with adequate heat-treatment condition.