(Mg,Co)O Solid‐Solution Precursors for the Large‐Scale Synthesis of Carbon Nanotubes by Catalytic Chemical Vapor Deposition

Single‐ and double‐walled carbon nanotubes were produced in high yield using the selective reduction of solid solutions of Mg 1– x Co x O in a methane and hydrogen atmosphere at 1000°C. The solid solutions were prepared using combustion synthesis with urea as the fuel. The BET surface areas ranged from 10 to 65 m 2 /g depending on the fuel content. A single crystalline phase was obtained only for fuel‐rich compositions. Increased fuel content increased the surface area by a factor of 6. However, very high fuel contents (>4 times the stoichiometric amount) caused a demixed solid solution. Surface‐area measurements and Raman spectra showed that the quantity of nanotubes formed depended on the surface area and composition of the precursor oxide.