Ditching Platinum for the Ocean Could Make Hydrogen Cheap
Hydrogen would be a terrific source of clean energy. The problem? It's hard and expensive to attain, either through mining it or producing it.
Scientists have developed a new catalyst to help produce hydrogen, meaning they could remove one of its most expensive components: platinum. It could also react with seawater, making it even cheaper.
By removing platinum from the equation, the discovery could make hydrogen more cost-effective in the future.
Hydrogen packs a powerful punch—that's why it's so often used in rocket fuel. It's also the most abundant element in the universe. One of the things that holds back its widespread adoption as an energy source, however, is that on Earth, hydrogen typically combines with other elements. Getting hydrogen often means either extracting or producing it, both of which can be expensive.
But now, scientists at the Pacific Northwest National Laboratory (PNNL) have found a pairing of minerals that surpasses other precious metal materials when it comes to producing hydrogen.
Testing a molybdenum-phosphide (MoP) catalyst with wastewater in a small reactor called a microbial electrolysis cell (MEC), scientists found that the MoP worked better than platinum.
The most frequently used method of producing hydrogen is known as electrolysis. Bringing together chemicals called electrolytes with electricity, a catalyst triggers a reaction that creates hydrogen. Platinum is currently the best of these catalysts, although its high price is a big drawback. If platinum could be discarded, that could bring hydrogen production costs down rapidly.
And that's not all. The MoP catalyst excelled at working with another abundant source: seawater.
"If you can produce hydrogen from seawater, the resource pool is pretty much unlimited," says Yuyan Shao, a material scientist at PNNL who led the catalyst research, in a press statement. PNNL is managed by the Department of Energy's Office of Science and is based out of the state of Washington.
Using an MEC, the team was able to combine the electrolysis technique with hydrogen fermentation, a low-yield process that consumes less energy. Unable to afford expensive platinum catalysts, the team needed something that could reduce production costs to approximately $2 per kilogram of hydrogen.
With a strong microscope, the team discovered that the catalyst assembled into a mixture of two distinct crystal phases: MoP and MoP2. With slightly different atomic structures, they produced different reactions. MoP2 released hydrogen atoms from water molecules, while MoP was able to convert hydrogen atoms into hydrogen gas molecules. It was a welcome surprise.
"We did not expect the simultaneous formation of the two crystal phases," says Shao. "The two phases work way better than the single phase."
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