Multi‐wall carbon nanotubes by catalytic decomposition of carbon monoxide on Ni/MgO

The redox behavior of the catalyst and the catalytic decomposition of carbon monoxide (CO) were investigated in the synthesis process of multi-wall carbon nanotubes (MWCNT) using Ni/MgO catalyst. The surface morphology of the heated Ni layer was observed by TEM to confirm the formation of NiO particles (50 nm or less) and NiO (222). The chemical reaction behavior of the catalyst in CO the atmosphere was displayed via TG-DSC analysis, and the reduction of NiO was revealed due to the mass decrease of 2.71 wt% and the exothermic peak at around 400 degrees C. The deposition of carbon was identified with an increase in mass and the exothermic peak near 600 degrees C. Ni (111) and carbon (002) facets was taken place in a diffraction pattern of carbon deposited catalyst, indicating the reduction in NiO and the graphitic carbon deposition. The crystallinity of the graphitic carbon was analyzed as the ratios of 0.998 forI(D)/I(G)and 0.26 forsp(3)/sp(2)in Raman and photoelectron spectra. The encapsulated Ni in MWCNT was observed through TEM-EDS, verifying the activation of the catalyst by CO.