Visible photoluminescence from ruthenium-doped multiwall carbon nanotubes

Visible photoluminescence at 515 nm of ruthenium-doped multiwall carbon nanotubes, fabricated on quartz substrates using a chemical vapor deposition technique, is reported. The well-aligned nanotubes serve as templates for the luminescent, residual ruthenium–iron catalyst particles contained within the nanotubes, restricting the particle size to about 10 nm. The synthesis technique can be readily extended to other luminescent dopants; moreover, since nanotube arrays can be readily grown from patterned substrates, nanotube-based optoelectronic devices may be achieved.