A novel fabrication method of vertically aligned carbon nanotubes by single-stage floating catalyst CVD

Abstract

The single-stage floating catalyst chemical vapor deposition (SS-FCCVD) method using the ferrocene route (e.g., ferrocene: catalyst and camphor: carbon source) offers significant but largely unexplored versatility for the production of carbon nanotubes (CNTs). Our study used the SS-FCCVD method to grow vertically aligned carbon nanotubes (VACNTs) on an alumina ceramic reactor surface at 850 °C under a nitrogen atmosphere. The experimental setup included a camphor/ferrocene ratio of 20:1 and a specific temperature gradient of 21 °C/cm. To minimize the catalyst agglomeration, we positioned the chemical sources at a distance of 15 cm from the inlet of the CVD reactor. Alumina ceramic surfaces proved highly effective for VACNT production, showing minimal agglomeration of iron particles, facilitating the formation of reactive sites essential for VACNT growth. The VACNTs grew readily on alumina ceramic surfaces, forming bundled, forest-like structures with segment lengths up to 1.2 mm and diameters around 60 nm. When compared to conventional substrates, the surface area of the reaction zone substrate increases by up to 705%, resulting in a significant boost in VACNT yield. A detailed evaluation of characterization results confirmed the growth mechanism and behavior of Fe particles such that carbon-encapsulated particles are attached to the inner and outer surfaces of the CNTs. These VACNT surfaces exhibited superhydrophobic properties, similar to the lotus leaf effect. The synthesized iron-dispersed CNTs exhibit exceptional efficiency in Chromium (VI) removal, with an impressive adsorption capacity of 0.206 mmol/m², positioning them as a promising solution for effective water treatment. This scalable SS-FCCVD method using the ferrocene route achieved the longest VACNTs reported to date.