Sandia National Laboratories (Albuquerque, NM) recently demonstrated that hollow organic nanotubes, married to an inorganic catalyst, can harness sunlight to turn water into pure hydrogen and oxygen. By 2006, Sandia researchers hope to have prototypes from which a new kind of solar cell could be made that would convert water into fuel. Such cells might replace fossil fuels in automobiles and thus reduce dependence on foreign oil.
Organic nanotubes are used throughout nature to transport electrons and to convert light into energy. The Sandia researchers believe they can harness the same mechanism to power automobiles with water. Sandia showed that porphyrin nanotubes can be prepared in aqueous solution by virtue of the ionic self-assembly of two oppositely charged porphyrins. By adding metal ions to the solution, the researchers were able to coat the outside of a nanotube with catalytic platinum as well as grow a gold wire — complete with a contact ball for connecting the hydrogen-harvesting part of the nanodevice to the part that harvests oxygen — down the middle of the two connected nanotubes. That serves as the connector between the two pieces of the nanodevice. The tube itself is photocatalytic and generates hydrogen.
The next step for the group is to create a device that marries the hydrogen-producing and oxygen-producing parts at the nanoscale. The Sandia prototype cell will be designed to harvest light to split water molecules, while keeping the hydrogen and oxygen separate so they can be stored as two parts of a hydrogen fuel.
