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

Using the citric acid complexing method, perovskite-like mixed oxides La2Ni O4 were prepared. Before and after reduction, its structure was characteriz ed 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 a fter 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 p articles, which is one of the key factors for carbon nanotube growth. The c arbon nanotubes from the catalytic decomposition of CH4 were obtained using La2NiO4 oxides as the catalyst precursor. The morphology of the carbon nan otubes obtained has been examined by transmission electron microscopy and s canning electron microscopy. High resolution transmission electron microsco py images and Raman spectra of carbon nanotubes show they are multi-walled nanotubes of good quality. (C) 2001 Elsevier Science Ltd. All rights reserv ed.