Rice University researchers have developed a simple solar-powered device, similar to other “artificial leaf” designs, that can turn water and sunlight into hydrogen fuel. However, this new device is self-sufficient and relatively cheap to produce in comparison to previous water-splitters.
How does it work? The process is made up of a perovskite solar cell, which is connected to electrodes comprised of a catalyst that electrolyzes the water. When the solar cell absorbs sunlight, it produces energy that powers the catalyst, which then splits the water into hydrogen and oxygen. Then, these bubble up to the surface of the water, where they can be collected for use.
The most useful feature of this new design is how much it’s self-contained. The electrodes and solar cells are all in one unit; the solar cell components are protected from water damage because they’re encased inside a polymer shell while still letting sunlight through. Finally, the electrodes rest on the outside, where they can split the water.
In the design, the team tweaked the perovskite solar cell so that it doesn’t need expensive components like platinum. Instead, they used cheap elements like carbon. The reason for this is that it will be less costly to produce the devices and more viable for commercial production. The same strategy of swapping precious metals for cheap ones now runs through industrial electrolysis, including a nickel cobalt electrode that matches platinum in alkaline water splitting.
The sunlight-to-hydrogen efficiency is relatively high for these kinds of systems, with around 6.7%. The researchers aim for the device to be able to be dropped into water with direct sunlight and left alone to run for long periods. The team published the study in the journal ACS Nano.
Jun Lou, the study’s lead author, said:
“With a clever system design, you can potentially make a self-sustaining loop. Even when there’s no sunlight, you can use stored energy in the form of chemical fuel. You can put the hydrogen and oxygen products in separate tanks and incorporate another module like a fuel cell to turn those fuels back into electricity.”
Among other artificial leaf ideas are ones designed by researchers from the University of Illinois explicitly created to absorb CO2 from the air. It can absorb ten times more CO2 from the air than a real leaf. While another artificial leaf, designed by scientists from the University of Cambridge, converts sunlight, CO2, and water into synthetic gas.
In March 2019, scientists from Stanford University also figured out how to turn seawater into fuel, a different approach that pairs fuel-making with pollutant cleanup is described in this solar leaf that needs a pollutant to make hydrogen from seawater. Eventually, these designs could widely be used in transportation, from cars to airplanes. And since the process produces oxygen, it could be used on submarines, supplying the ship with fuel and oxygen for the people within the vessel. Divers could benefit from the technology, too, in a device to replace an oxygen tank or power the diver’s gear.
