Nitrogen-doped carbon nanotubes have also been used to reduce the oxygen at the cathode in fuel cells. In fuel cell research, carbon nanotubes have been added to the platinum/carbon catalyst mixture at the anode to improve the efficiency of the catalyst reactions in the fuel cell. Carbon nanotubes can store hydrogen, enable electrons to flow, or increase catalyst activity. Figure 2 shows a schematic of a single-walled and a multiwalled carbon nanotube.įigure 2: Schematic representation of a single-walled nanotube (SWNT) and a multiwalled nanotube (MWNT) 2įuel Cell and Hydrogen Storage ApplicationsĬarbon nanotubes have found many uses in energy applications. These are usually prepared using an electric arc drawn between two carbon electrodes, laser ablation, or chemical vapor deposition. Both single-walled and multiwalled carbon nanotubes have highly ordered, smooth graphitic surfaces. These structures look like rolls of cylinders or like newspaper pages rolled up in into a cylinder. Multi-walled nanotubes (MWNT) consist of multiple layers of carbon nanotubes to form a cylindrical shape. The main hindrance to the widespread use is that they are expensive to produce. The SWNTs can replace electric wires on the micro-electromechanical (MEMs) scale. Single-walled nanotubes (SWNTs) are important because they exhibit exceptional electrical properties and are a good candidate for miniaturizing electronics. Graphitic nanofibers range from 50 nm to 100 nm in length and 5 to 100 nm in diameter. Graphitic nanofibers are made by breaking hydrocarbons or carbon monoxide over suitable catal ts ys, and the structures can be a platelet, ribbon or herringbone arrangement. There are many types of carbon nanotubes, but the ones commonly used can be categorized as graphitic nanofibers, single-walled nanotubes (SWNTs) or multi-walled nanotubes (MWNTs). SEM image of aligned carbon nanotubes approximately 20 um long 1 Each rope consists of a bundle of single-wall nanotubes aligned in a single direction.įigure 1. These ropes are 10 to 20 nm across and up to 100 microns long. Under an electron microscope, the nanotube material looks like a mat of carbon ropes as shown in Figure 1. They can be used as electrical and heat conductors, hydrogen storage, as well as many other applications.Ĭarbon nanotubes are potentially useful for many applications in nanotechnology, electronics, optics, and materials science for their electrical conductivity, heat conductivity and high strength. They are 100 times stronger than steel at 1/6 of the weight. The definition of a carbon nanotube is: Large molecules of pure carbon that are long and thin tubes. The size of these structures is often a nanometer across and tens of microns long. A carbon nanotube is a hexagonal network of carbon atoms that have often been rolled into a cylinder. Carbon nanotubes are unique structures with exceptional electronic and mechanical properties. These include hydrogen storage in carbon nanotubes. There are many novel hydrogen methods that are currently being investigated that offer the potential for higher energy density than conventional methods.
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