In order to improve the carbon nanotube reactivity, decorated carbon nanotubes with metallic particles have been used as fast responsive sensors. During the metal anchorage process, acid treatments have been used to improve the reactivity of the relatively inert nanotube surfaces.Unfortunately, this functionalization process reduces the mechanical and electronic properties of the tubes caused by the creation of defects. However, the surface of CNx nanotubes is chemically active without using acids treatments, due to the presence of nitrogen atoms embedded in carbon tubule (note that nitrogen has an extra electron
when compared to carbon)