Modulation of Single-Walled Carbon Nanotube Diameter by Component Ratios in Magnesium-Aluminium Layered Oxides

The diameter of single-walled carbon nanotubes (SWNTs) has a decisive influence on their electronic structure and optoelectronic properties. This study innovatively explored the mechanism of regulating the diameter of SWNTs by the Mg/Al ratio in magnesium-aluminium layered double oxide (LDOs) catalysts. Fe/Co/Mg/Al-LDOs catalysts with different Mg/Al ratios were synthesized by co-precipitation, and the effect of the Mg/Al ratio on the diameter of SWNTs grown by catalytic growth at 700°C was investigated. The experimental results showed that increasing the Al component is beneficial to selectively growing small- diameter SWNTs, while increasing the Mg component tends to promote the growth of larger-diameter SWNTs. Catalyst characterization indicated that the introduction of Al promoted the migration of Co cations into the support. The unreduced Co 2+ could anchor the metal nanoparticles reduced on the support surface, effectively inhibiting the agglomeration of metal nanoparticles, thereby favoring the growth of small-diameter SWNTs. This finding provides a simple and efficient strategy for the controllable synthesis of SWNTs with specific diameters, laying a foundation for the development of high-performance carbon-based nanoelectronic devices.