From Scientific American:
Splitting water into its constituent hydrogen and oxygen elements is an important starting point for the development of clean renewable fuels. Producing hydrogen from water could also become a method to store excess renewable energy.
It’s a process plants have already mastered via photosynthesis and humans are now working to replicate.
“While photosynthesis is extremely good at oxidizing water, the truth is many man-made processes of doing these things are not that good,” said Thomas Jaramillo, a researcher at the SUNCAT Center for Interface Science and Catalysis in Stanford University’s Department of Chemical Engineering.
Many of the artificial methods of making hydrogen and oxygen from water require materials that are too expensive, require too much energy or break down too quickly in real-world conditions, like the acidic electrolytes in fuel cells.
But splitting water to generate hydrogen may be an important way to cut greenhouse gas emissions. Jaramillo observed that the world produces more than 50 billion kilograms of hydrogen each year and more than 95 percent of it comes from fossil fuels through processes like steam reforming methane.
Jaramillo and his collaborators sought to develop a catalyst for the oxygen evolution reaction, the notoriously slow half of the water-splitting process. A catalyst is a substance that speeds up a chemical reaction or lowers the energy required to get it started without getting used up itself. Making these materials last longer, work faster and use less energy would cut prices and improve efficiency in producing renewable hydrogen.
In a paper published last week in the journal Science, the research team presented an oxygen evolution catalyst that worked in harsh conditions and beat all of its competitors.
“The biggest achievement in this paper is that we were able to find a stable catalyst that works in acid,” said co-author Yasuyuki Hikita, a staff scientist at SLAC National Accelerator Laboratory. …