Enhanced Nanoporosity of Single-Walled Carbon Nanotube Network

Single-walled carbon nanotubes (SWCNTs) are synthesized with a 25 wt% carbon yield via catalytic chemical vapor deposition (CVD) using a Fe-Mo/MgO catalyst system. Following HCl purification, the SWCNTs reach a carbon purity of 95.6 wt%, accompanied by a remarkable increase in specific surface area (940 m(2) g(-1)) and pore volume (2.7 mL g(-1)). Acid treatment significantly enhances the mesoporosity of the SWCNT network, promoting the adsorption of guest molecules on the nanotubes' external surfaces. The structural characteristics of the SWCNTs are thoroughly examined using field-emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, thermogravimetric analysis, and Raman spectroscopy. Nitrogen adsorption at 77 K reveals that HNO3/H2SO4 treatment induces micropore formation through nanotube aggregation, with a slight decrease in mesoporosity, maintaining predominantly mesoporous adsorption properties. Comparative analysis of SWCNTs synthesized by different methods-including fluidized-bed CVD, HiPco, laser ablation, arc discharge, and Tuball-demonstrates that the crystallinity of SWCNTs plays a pivotal role in modulating nanoporosity during strong acid treatments. This work underscores the importance of structural properties, particularly crystallinity, in optimizing SWCNTs for applications in energy storage and advanced adsorption systems.