Continuous Ni-layer on multiwall carbon nanotubes by an electroless plating method

Electroless plating has been successfully applied for nickel coatings on multiwall carbon nanotubes (MWNTs) grown by chemical vapor deposition (CVD). The samples before and after coating were checked using transmission electron microscopy (TEM) and X-ray diffraction (XRD). The results showed that the coating process can be divided into two steps: nickel was first deposited as nanoparticles at the activated sites on the pre-treated surface of carbon nanotubes in the initial stage; it was then thickened later, as the reaction time increased and eventually formed a continuous layer. Finally a uniform Ni-layer on individual tubes with thickness of 20–40 nm can be obtained after coating. A simple model for the mechanism of the coating is also discussed.