Carbon nanotube growth on Ni-particles prepared in situ by reduction of La2NiO4

Using the citric acid complexing method, perovskite-like mixed oxides La2NiO4 were prepared. Before and after reduction, its structure was characterized by means of X-ray diffraction and XPS. Due to the formation of La2NiO4, Ni2+ and La3+ ions were evenly distributed. Nickel exists chiefly as Ni-0 after reduction and the size of Ni particles was estimated to be ca. 28 nm. After reduction of La2NiO4 oxide, the rare earth oxide, La2O3, prevents Ni particles from agglomerating and promotes the dispersion of nano-scale Ni particles, which is one of the key factors for carbon nanotube growth. The carbon nanotubes from the catalytic decomposition of CH4 were obtained using La2NiO4 oxides as the catalyst precursor. The morphology of the carbon nanotubes obtained has been examined by transmission electron microscopy and scanning electron microscopy. High resolution transmission electron microscopy images and Raman spectra of carbon nanotubes show they are multi-walled nanotubes of good quality. (C) 2001 Elsevier Science Ltd. All rights reserved.