Synthesis of Super-Long Carbon Nanotubes from Cellulosic Biomass under Microwave Radiation

This study reports a novel method for synthesizing super-long carbon nanotubes (SL-CNTs) from cellulose via a microwave treatment process without an external catalyst. CNTs with a length of 0.7-2 mm were obtained via microwave treatment of cellulose biochar temperatures of 1200-1400 degrees C. Scanning electron microscope (SEM), together with high-resolution transmission electron microscope (HRTEM) results, were used to investigate the changes in the length and morphology of CNTs with respect to treatment temperature. The morphology of CNTs changed from twisted, curved, and threadlike to straight structures. The average length of CNTs after microwave pyrolysis at 600 degrees C was approximately 600-1800 nm, which after microwave treatment at 1300 degrees C and 1400 degrees C increased to about 1-2 mm. X-ray diffractometer (XRD) results confirmed the crystalline structure of CNTs with two prominent peaks at 2 theta = 26.3 degrees and 2 theta = 43.2 degrees correlating with the graphite (002) and (100) reflections. The I-D/I-G ratio obtained from Raman spectra of the CNTs decreased to the lowest value of 0.84 after microwave treatment at 1400 degrees C, implying a high degree of carbon order. The presence of Fe and trace amounts of other elements were confirmed by the energy-dispersive X-ray spectrometer (EDS) and were postulated to have catalyzed the growth of CNTs. The mechanism of the SL-CNTs growth under microwave treatment was proposed and discussed.

Automated summary

This study presents a new method for synthesizing super-long carbon nanotubes (SL-CNTs) from cellulose using microwave treatment. The length and morphology of the CNTs were investigated by adjusting the treatment temperature. The results showed that the microwave treatment temperature had a significant impact on the growth of CNTs, and a growth mechanism was proposed.