A floating, solar-powered device that can turn contaminated water or seawater into clean hydrogen fuel and purified water has been developed by researchers.
Developed by researchers at the University of Cambridge, could be useful in resource-limited or off-grid environments since it works with any open water source and does not require outside power.
The University of Cambridge has said that the technology takes its inspiration from photosynthesis.
However, unlike earlier versions of the ‘artificial leaf’, which could produce green hydrogen fuel from clean water sources, this new device operates from polluted or seawater sources and can produce clean drinking water simultaneously.
The device will benefit areas that suffer from a lack of clean water
Tests of the device have shown that it was able to produce clean water from highly polluted water, seawater, and even from River Cam in central Cambridge. The results are reported in the Nature Water journal.
Dr Chanon Pornrungroj from Cambridge’s Yusaf Hamied Department of Chemistry explained that creating this device has been a challenge: “Bringing together solar fuels production and water purification in a single device is tricky.
“Solar-driven water splitting, where water molecules are broken down into hydrogen and oxygen, need to start with totally pure water because any contaminants can poison the catalyst or cause unwanted chemical side-reactions.”
Continuing, co-lead author Ariffin Mohamad Annuar highlighted that this device will benefit areas that suffer from a lack of clean water: “In remote or developing regions, where clean water is relatively scarce and the infrastructure necessary for water purification is not readily available, water splitting is extremely difficult.”
A device that could work using contaminated water could solve two problems at once: it could split water to make clean fuel, and it could make clean drinking water.
Producing clean water and fuel could help to address the energy and water crisis
The research group deposited a photocatalyst on a nanostructured carbon mesh that is a good absorber of both light and heat, generating the water vapour used by the photocatalyst to create hydrogen.
It saw the porous carbon mesh, treated to repel water, served both to help the photocatalyst float and to keep it away from the water below so that contaminants don’t interfere with its functionality.
Ariffin Mohamad Annuar expressed that the new device uses more of the sun’s energy: “The light-driven process for making solar fuels only uses a small portion of the solar spectrum – there’s a whole lot of the spectrum that goes unused.”
The team used a white, UV-absorbing layer on top of the floating device for hydrogen production via water splitting. The rest of the light in the solar spectrum is transmitted to the bottom of the device, which vaporises the water.
A device that can make clean fuel and clean water at once using solar power alone could help to address the current energy and water crises.
Giving an example, the University of Cambridge states that indoor air pollution caused by cooking with dirty fuels, such as kerosene, is responsible for more than three million deaths annually, according to the World Health Organization. Therefore, cooking with green hydrogen instead could help reduce that number significantly.
The research was supported in part by the European Commission’s Horizon 2020 programme, The European Research Council, the Cambridge Trust, the Petronas Education Sponsorship Programme, and the Winton Programme for the Physics of Sustainability.