Carbon nanotubes are cylindrical chains composed purely of carbon atoms. Due to their unique structure, they exhibit unusual strength and unique electrical properties, and are efficient conductors of heat. The tubes have huge potential in the fields of nanotechnology, electronics and superconductivity, among others.
Now scientists at Sandia National Laboratories have demonstrated that organic nanotubes, married to an inorganic catalyst, can harness sunlight to turn water into pure hydrogen and oxygen.

Water molecules confined in a nanotube (Courtesy: AIP)Such organic nanotubes are already in use in nature. For example, our blood uses porphyrin nanotubes, which provide the power by which hemoglobin forms new proteins. The Sandia researchers believe they can harness the same mechanism to power automobiles with water. In fact, their laboratory created tube mimics one naturally occuring tube called the chlorosome, which is found in some photosynthetic bacteria! One day, fuel cells composed of such nano-structures might be able to reduce our dependence on fossil fuels.
The researchers were able to synthetically create the nanotubes in an aqueous solution. The tube has two different regions for generating hydrogen and oxygen respectively, in the presence of sunlight. The two gases are emitted from the two sides of the tube, where they can be captured and stored separately.
The next step is to create an array of these tubes, so that it can act as a solar cell that will generate hydrogen and oxygen. The porphyrin nanotubes are similar in size to carbon nanotubes, measuring up to 1 micron long but only 50 to 70 nanometers in diameter, with walls just 20 nm thick. They self-assemble easily (in an aqueous solution, for example) and it is quite conceivable to easily and cheaply produce them en masse.
Further usages of such a device could be in the fields of electronics, photonics, and chemical sensors.