Controlled catalytic domain formation by mixed iron halide compounds to decrease the waviness of carbon nanotube arrays

In this study, we present a method for controlling the waviness of carbon nanotube (CNT) arrays by adopting a two-phase catalytic system. In addition, we investigate the relationship between the catalyst state and the synthesis process of CNT arrays. As catalysts, we use two iron halides, iron(II) chloride and iron(III) chloride, combined in different ratios. The catalysts decompose and react with a silica surface on the substrate during the chemical vapor deposition process. The decomposed ions oxidize and precipitate over the substrate. An increased iron(III) contribution decreases the waviness of CNT arrays. Furthermore, we demonstrate that the catalyst state affects the alignment, diameter, length, and waviness of CNTs.