Researchers have found a clean, efficient, and economical method of separating hydrogen from water and sunlight.
The new method employs both "optical properties of three-dimensional photonic crystals," and two to three "gold nanoparticles to develop a highly active catalyst powder," a Universitat Politècnica de Catalunya (UPC) news release reported.
In using both photonic crystal and metal nanoparticles, the scientists were able to create a photocatalyst that produces more hydrogen than would have been possible with past models. The key is perfectly "tuning" the two materials to get the best possible results.
"You have to choose the right photonic crystal and the right nanoparticles," Jordi Llorca, a researcher at the Universitat Politècnica de Catalunya· BarcelonaTech Institute of Energy Technology, said in the news release.
All photocatalysts that include gold nanoparticles, titanium dioxide (photonic) crystals, and ultraviolet go through the same process. In this type of hydrogen creation "light excites the TiO2 [titanium dioxide] electrons and promotes them to the conduction band, leaving holes on the other side. The electrons interact with the gold nanoparticles and are captured by them" the news release reported.
What makes this new method special is the use of 3D photonic crystals. The crystals capture the visible light in the solar spectrum at the exact energy levels that the gold nanoparticles "resonate." This allows researchers to put the visible part of the solar spectrum to use instead if solely relying on ultraviolet light.
"This translates into a significant boost in the performance of the process," the news release reported.
The new method would allow for a reactor to be built outdoors, using a solar collector to capture sunlight.
Most of today's hydrogen plants produce about 300 tons of hydrogen a day; this new method has been proven to produce 0.025 liters of hydrogen an hour using only one gram of catalyst. Modern plants also burn fossil fuels at a temperature of about 800 degrees Celsius; this new method operates and room temperature and needs only water and sunlight to produce hydrogen. This provides monumental "environmental gains."
"The researchers say they have managed to pass the milestone of converting [five percent] of solar energy into hydrogen at room temperature, the threshold at which the technology is considered feasible. Renewable hydrogen production is essential if the gas is to become the energy carrier of the future," the news release reported.
Researchers at the Institute of Energy Technology (INTE), the University of Auckland (New Zealand), and King Abdullah University of Science and Technology (Saudi Arabia) also participated in the study.
