Porous target enhances production of single-wall carbon nanotubes by laser ablation

When a carbon target containing Ni nitrate and Co nitrate was used in laser ablation performed at 1470 K, about twice as many single-wall carbon nanotubes (SWNT) could be formed as when using carbon targets containing Ni and Co metals, or Ni oxide and Co oxide. The enhanced production by using the CNiCo(nitrate) target was mainly due to its porous structure and partially due to the small size of the metal particles. This target emitted nitrogen, oxygen, and water while being heated up to 1470 K, so it became porous. Such a porous structure was not observed for the target containing metals or oxides. When the Ni and Co metal particle sizes were reduced from 5–10 to 20 nm, SWNT production increased 1.4 times.