Water for Fuel
Over the past decades, have become the backbone of the world's industries. They have also been the number one cause of man-made . Fortunately, things are beginning to change, as fossil fuels are on the decline thanks to the rise of renewable energy sources.
An alternative energy source with great potential is solar power. One variant of solar energy is solar fuel, which is produced by using sunlight to convert water or carbon dioxide into combustible chemicals. Because of the relative abundance of solar fuel components, it's considered a desirable goal for clean-energy research. However, these reactions, such as producing hydrogen by splitting water, aren't possible by using just sunlight. Materials to efficiently facilitate the process are necessary.
Scientists have been working on creating practical solar fuels by developing low-cost and efficient materials to serve as photoanodes. Photoanodes are similar to the anodes in a battery and activate the production of solar fuel by aiding the flow of Electrons during the process. Scientists from the Department of Energy's Lawrence Berkeley National Laboratory (Berkeley Lab) and the California Institute of Technology (Caltech) have successfully doubled the number of potential photoanodes in just two years.
Now, researchers led by Caltech's John Gregoire and Berkeley Lab's Jeffrey Neaton have developed a new, faster method to identify new materials to use as photoanodes, and they've found 12 promising candidates. They published their research in the online edition of the Proceedings of the National Academy of Sciences.
Neaton, director for the Molecular Foundry at Berkeley Lab, said that the study advanced this field of research by not only providing an improved method to look for photoanodes, but also by giving researchers insight into the new photoanodes.
"What is particularly significant about this study, which combines experiment and theory, is that in addition to identifying several new compounds for solar fuel applications, we were also able to learn something new about the underlying electronic structure of the materials themselves," Neaton said in a Caltech press release.
To discover these new photoanodes, the team combined computational and experimental approaches. A Materials Project database was mined for potentially useful compounds. Hundreds of theoretical calculations were performed using computational resources at the National Energy Research Scientific Computing Center (NERSC), together with software and expertise from the Molecular Foundry. Once the best candidates for photoanode activity were identified, it was time to test those materials in the laboratory.
The materials were simultaneously tested for anode activity under different conditions using high-throughput experimentation. This was the first time these kinds of experiments had been run this way, according to Gregoire.
"The key advance made by the team was to combine the best capabilities enabled by theory and supercomputers with novel high throughput experiments to generate scientific knowledge at an unprecedented rate," Gregoire said in the press release.
They found that compounds with vanadium, oxygen, and a third element had highly tunable electronic structure that made them uniquely favorable for water oxidation.
"Importantly, we were able to explain the origin of their tunability, and identify several promising vanadate photoanode compounds," Neaton said in the press release.
This research has provided us with more ways to make use of water — one of the world's most abundant resource — as an energy source. As advancements like this allow us to develop renewable energy cheaply and more efficiently, governments, investors, and individuals alike will have more reasons to leave fossil fuels in the past.