A newly developed nanomaterial can release hydrogen from seawater much more cheaply and efficiently than existing methods, potentially giving us another way of unlocking this most sustainable of energy sources.
Finding a way to produce hydrogen from water that isn't prohibitively costly in price and energy could significantly reduce our reliance on fossil fuels.
And the team from the University of Central Florida say the new extraction method is particularly well suited to their home state, with an abundance of both sunshine and seawater – the two natural elements that make the whole process tick.
"We've opened a new window to splitting real water, not just purified water in a lab," says senior researcher Yang Yang, who has been working on this type of technology for a decade. "This really works well in seawater."
Put a hydrogen fuel cell in your car, and the only waste product is water, which can be turned back into hydrogen and oxygen – it's a truly sustainable, clean, and environmentally friendly way of providing power.
The problem is producing hydrogen, from water or another source, in a cost-effective way that doesn't cost more energy and create more carbon than it saves. It's a puzzle that teams of scientists across the world are trying to solve.
And scientists have looked at getting hydrogen from seawater before – it can be done, but it uses a lot of electricity. The qualities of the water in the oceans, including the salt in it, make the process particularly tricky.
For this study, Yang and his team developed a new nanomaterial to act as a photocatalyst, spurring the chemical reaction that occurs when light hits a surface: in this case, producing hydrogen gas from water.
Crucially, the nanomaterial captures a broader spectrum of light than other materials, so it can use more of the Sun's energy. It also is specially designed to stand up to the harsh conditions found in seawater.
The hybrid material is based on titanium dioxide, the most common photocatalyst, but it's etched with microscopic nanocavities coated with a compound called molybdenum disulfide.
That's the magic formula that makes the release of hydrogen much more efficient, at a reasonable cost. The researchers say it's at least twice as efficient as current photocatalysts.
There's still quite a way to go with this technology, which needs to be scaled up and commercialised if it's going to give us a hydrogen-fuelled future, but the early tests run by the researchers show promising results.
As an added bonus, using sunlight directly rather than using electricity from solar panels means there's no need to store electricity in batteries. The hydrogen gas can be stored and transported instead, which is easier to do.
"We can absorb much more solar energy from the light than the conventional material," says Yang. "Eventually, if it is commercialised, it would be good for Florida's economy."
The research has been published in Energy & Environmental Science.