Nanoptek Corp. has been awarded U.S. Patent No. 7,485,799 ‘Stress-Induced Bandgap-Shifted Semiconductor Photoelectrolytic, Photocatalytic, Photovoltaic Surface and Method for Making Same’ for a more efficient way of making hydrogen from water and sunlight using Nanoptek's improved photocatalyst and photoelectrolytic cell.
Nanoptek's patented technology for producing hydrogen, unlike the way most hydrogen is produced, is completely carbon-free and renewable, the company notes. Nanoptek envisions that this innovation will promote the use of hydrogen for producing green electricity, in addition to providing hydrogen for use as an important chemical feedstock for manufacturing, especially in remote off-grid and off-pipeline regions in the U.S. and around the world.
Titania (titanium dioxide), when illuminated with ultraviolet light, is a photocatalyst in that it reduces the voltage required to dissociate water into hydrogen and oxygen. However, the scarcity of ultraviolet light in sunlight severely limits titania's efficiency. Nanoptek's innovation allows titania to absorb and be activated by more of the light in the solar spectrum, not just ultraviolet, in a process known as ‘bandgap shifting.’
Nanoptek's scientists achieve this bandgap shift by growing titania films onto nanostructures that are essentially very small arches. Conceptually, these arches force each successive layer of titania molecules to stretch in order to line up with the previous layer during growth of the film.
As the titania is stretched, electrons in the titania molecules are less tightly bound, so they are more easily excited by light with lower energy than ultraviolet light, in this case, some of the more abundant visible light. The excited electrons drive a process known as photoelectrolysis, the end result of which is dissociation of water into hydrogen and oxygen gases.
SOURCE: Nanoptek Corp.
