Syntheses and catalytic applications of the high-N-content, the cup-stacking and the macroscopic nitrogen doped carbon nanotubes

The high-N-content, the cup-stacking and the macroscopic nitrogen doped carbon nanotubes (NCNT) were synthesized via an easily manufactured catalytic chemical vapor deposition (CCVD) method. Nitrogen physisorption, transmission electron microscopy (TEM), thermogravimetric analysis (TGA), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) were used to characterize the as-obtained NCNTs. High reaction temperatures were found to be the key point to the formation of inner-cup-stacking NCNTs. However, the synthesis of the outer-cup-stacking NCNT needs special demands not only to the reaction temperature but also to the catalyst and the carrier gas. The possibility of CO oxidation by NCNT was proved to be very small, and the outer-cup-stacking NCNT showed obvious advantage in the oxidative dehydrogenation (ODH) of butene to butadiene compared to a bamboo-like NCNT with an even higher N content.