Penn State researchers Thomas E. Mallouk and W. Justin Youngblood, in collaboration with Arizona State University, have developed a catalyst and dye system that use solar energy to split water into hydrogen and oxygen. The system is a proof-of-concept that was reported at the American Association for the Advancement of Science.
The Penn State direct solar to hydrogen system mimics photosynthesis that plants use for similar purposes. The Penn State system, however, uses an orange-red dye to absorb blue light, which offers the most energetic wavelengths. When sunlight strikes the dye, it excites an iridium oxide catalyst, which in turn splits the water into hydrogen and oxygen.
The Penn State scientists put the catalyst inside a titanium dioxide anode and used a platinum cathode, separated the two and immersed them in a saltwater solution. This method helps the hydrogen and oxygen from recombining back into water.
The point of the Penn State research is to find a direct solar to hydrogen solution that is renewable, cheap and uses less energy than electrolysis of water. In October 2007, I had talked about some Germany researchers at the Max Planck Institute who were getting close to a direct solar to hydrogen solution using a titanium disilicide semiconductor.
In January 2007, I had also talked about a British Company, Hydrogen Solar, Ltd. doing direct solar to hydrogen research as well. Hydrogen Solar is using iron oxide nanoparticle thin film technology to create the reaction. With so many researchers working on the solution worldwide, its only a matter of time until a breakthrough that can be scaled up for commercial purposes is developed.