Engineers at University of California, San Diego are creating a “nanoforest” that can capture solar energy and use it generate fuel from hydrogen.
Running cars, homes and buildings on hydrogen has long thought to be the ultimate clean solution, but getting there has been tough.
They say the tiny nanowire trees, made from abundant sources like silicon and zinc oxide, mimic the way trees naturally absorb energy from the sun through photosynthesis.
Using these inexpensive materials could be a key to mainstreaming hydrogen fuels. Until now, hydrogen fuel cells have depended on platinum, an expensive catalyst.
And they’ve also depended on electricity to separate hydrogen from water, usually from fossil fuels.
3D vertical nanotrees capture much more sunlight than do flat surfaces, which simply reflect it.
The structure also maximizes hydrogen gas output, using a process for separating water into oxygen and hydrogen called photoelectrochemical water-splitting.
“With this structure, we have enhanced, by at least 400,000 times, the surface area for chemical reactions,” says Ke Sun, an electrical engineering Ph.D. student who is leading the project.
If hydrogen fuel cells were cheap enough they would be ideal for energy storage for buildings, the grid, and in fuel cell vehicles.
In the long run, the team is aiming for a holy grail of energy production: artificial photosynthesis. It would also capture carbon from the atmosphere, reducing emissions and converting it to hydrocarbon fuel.