Metallic Nanowires From Carbon Nanotube Building Blocks: The Effect of Atomic Defects on the Nanotube Influencing Nanowire Growth

Manipulation and control of matter at the nano- and atomic level are crucial for the success of nano-scale sensors and actuators. The ability to control and synthesize multilayer structures using carbon nanotubes that will enable to build electronic devices within a nanotube is still in its infancy. In this paper, we present results on selective electric field assisted deposition of metals on carbon nanotubes realizing metallic nanowire structures. Silver and platinum nanowires has been fabricated using this approach due to its applications in chemical sensing sensing as catalytic materials to sniff toxic agents and in the area of biomedical nanotechnology for construction of artificial muscles. The electric field assisted technique allows the deposition of metals with high degree of selectivity on carbon nanotubes by manipulating the charges on the surface of the nanotubes. The thickness and the growth of the nanowires was altered by inducing defects on the initial surface of the nanotubes that affected the local current densities and electrochemical reduction of silver and platinum on those defect sites. SEM and TEM investigations revealed silver and platinum nanowires between 10 nm-100 nm in diameter. Relatively higher metal deposition was achieved in defect related sites or places where the nanotubes criss-crossed each other, due to the high current densities in these sites. The present technique is versatile and enables the fabrication of host of different types of metallic and semiconduting nanowires using carbon nanotube templates for nanoelectronics and myriad of sensor applications. Further, nanowires can also serve as model systems for studying quantum size effects in these dimensions.