Diameter-controlled growth of single-walled carbon nanotubes using Fe(OH)₃ colloid as catalyst precursor

By controlling the diameter size and chirality of single-walled carbon nanotubes (SWCNTS), a wide range of application potential could be realized in electronic, semiconductor, biomedical and electrochemical devices. Here, a positively charged Fe(OH)₃ colloid was used as a catalyst precursor, which was loaded onto MgO powder substrate through impregnation method. The Fe/MgO catalyst was successfully prepared. Subsequently, Ni and W elements were introduced to construct a bimetallic catalytic system. Finally, SWCNTs were grown by chemical vapor deposition (CVD) method. The Fe(OH)₃ colloid precursor can achieve the small size of catalytic active particle without the calcination process, also simplifying the growth process of SWCNTs. The anchoring and high-temperature stability provided by Ni and W elements effectively controlled the diameter distribution of SWCNTs. The experimental results showed that using Fe-W/MgO-50 catalyst (Fe:W:MgO = 1:1:50), which was annealed at 600 °C, the diameters of SWCNTs grown by CVD at 1000 °C mainly concentrated in the range of 0.91 nm ± 0.06 nm, accounting for approximately 90 %.