A Comprehensive Study of Pristine and Calcined f-MWCNTs Functionalized by Nitrogen-Containing Functional Groups

We present the study of pristine and calcined f-MWCNTs functionalized by nitrogen-containing functional groups. We focus on the structural and microstructural modification tuned by the previous annealing. However, our primary goal was to analyze the electronic structure and magnetic properties in relation to the structural properties using a multi-technique approach. The studies carried out by X-ray diffraction, XPS, and Fe-57 Mossbauer spectrometry revealed the presence of gamma-Fe nanoparticles, Fe3C, and alpha-FeOOH as catalyst residues. XPS analysis based on the deconvolution of core level lines confirmed the presence of various nitrogen-based functional groups due to the purification and functionalization process of the nanotubes. The annealing procedure leads to a structural modification mainly associated with removing surface impurities as purification residues. Magnetic studies confirmed a significant contribution of Fe3C as evidenced by a Curie temperature estimated at T-C = 452 +/- 15 K. A slight change in magnetic properties upon annealing was revealed. The detailed studies performed on nanotubes are extremely important for the further synthesis of composite materials based on f-MWCNTs.

Automated summary

This study focuses on investigating the structural and microstructural modifications of pristine and calcined f-MWCNTs functionalized by nitrogen-containing functional groups. The electronic structure and magnetic properties were analyzed using various techniques, revealing the presence of catalyst residues and the contributions of Fe3C. Surface impurities were removed through the annealing process, resulting in slight changes in magnetic properties. The detailed studies performed on nanotubes are crucial for the synthesis of composite materials based on f-MWCNTs.