Diameter-Specific Growth of Semiconducting SWNT Arrays Using Uniform Mo_2C Solid Catalyst

摘要

Semiconducting single-walled nanotube (s-SWNT) arrays with specific diameters are urgently demanded in the applications in nanoelectronic devices. Herein, we reported that by using uniform Mo_2C solid catalyst, aligned s-SWNT (～90%) arrays with narrow-diameter distribution (～85% between 1.0 and 1.3 nm) on quartz substrate can be obtained. Mo_2C nanoparticles with monodisperse sizes were prepared by using molybdenum oxide-based giant clusters, (NH_4)_(42)[Mo_(132)O_(372)(H_3CCOO)_(30)(H_2O)_(72)]. 10H_3CCOONH_4·300H_2O(Mo_(132)), as the precursor that was carburized by a gas mixture of C_2H_5OH/H_2 during a temperature-programmed reduction. In this approach, the formation of volatile MoO_3 was inhibited due to the annealing and reduction at a low temperature. As a result, uniform Mo_2C nanoparticles are formed, and their narrow size-dispersion strictly determines the diameter distribution of SWNTs. During the growth process, Mo_2C selectively catalyzes the scission of C-O bonds of ethanol molecules, and the resultant absorbed oxygen (O_(ads)) preferentially etches metallic SWNTs (m-SWNTs), leading to the high-yield of s-SWNTs. Raman spectro-scopic analysis showed that most of the s-SWNTs can be identified as (14, 4), (13, 6), or (10, 9) tubes. Our findings open up the possibility of the chirality-controlled growth of aligned-SWNTs using uniform carbide nanopartides as solid catalysts for practical nanoelectronics applications.