The Enhancing the Yield of Carbon Nanotubes Through the Nanocatalyst-Substrate Interface

In this study, the effect of the nanocatalyst/substrate interface on the yield and quality of carbon nanotubes (CNTs) synthesized by chemical vapor deposition (CVD) was investigated. Nickel oxide (NiO) nanoparticles were prepared using the sol–gel spin-coating method and deposited as thin films with different masses (66 mg, 99 mg, and 132 mg) on SiO2/Si substrates with an identical surface area of 12,56 cm2. The NiO nanoparticle thin films on the substrate surface were then placed into a CVD reactor and reduced in a hydrogen atmosphere, resulting in the formation of nickel nanoparticles that acted as active catalysts during CNTs synthesis. Ethanol vapor was used as the sole carbon source without any carrier gas, which enabled precise and comparative evaluation of the CNTs yield. X-ray diffraction (XRD) and Raman spectroscopy were employed to characterize the obtained CNTs. XRD results showed that CNTs with high crystallinity were produced when a 51,7 mg catalyst thin film was used. Raman spectroscopy confirmed the presence of RBM, G, D, and G′ peaks characteristic of CNTs structures. Increasing the catalyst mass led to a rise in RBM frequency and a decrease in CNTs diameter. However, an increase in catalyst mass also caused a reduction in CNTs yield. The highest yield (445%) was observed for Ni nanocatalysts with a mass of 51,7 mg. These findings demonstrate that the thickness of the catalyst layer and its surface distribution density on the substrate play a crucial role in determining the growth efficiency and structural quality of CNTs.

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