A floating, solar-powered device that can turn contaminated water or seawater into clean hydrogen fuel and purified water, anywhere in the world, has been developed by researchers.
The device, 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 any outside power. It takes its inspiration from photosynthesis, the process by which plants convert sunlight into food. 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 at the same time. Tests of the device showed it was able to produce clean water from highly polluted water, seawater, and even from the River Cam in central Cambridge.
"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," ” Dr Chanon Pornrungroj, Yusuf Hamied Dept of Chemistry, University of Cambridge (co-lead author)
"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," ” Ariffin Mohamad Annuar, Yusuf Hamied Dept of Chemistry, University of Cambridge (co-lead author)
Pornrungroj and Mohamad Annuar, who are both members of Professor Erwin Reisner’s research group, came up with a design that did just that. They 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. 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 do not interfere with its functionality.
Read the full University of Cambridge article
Chanon Pornrungroj, Ariffin Bin Mohamad Annuar et al. ‘Hybrid photothermal-photocatalyst sheets for solar-driven overall water splitting coupled to water purification.’ Nature Water (2023). DOI: 10.1038/s44221-023-00139-9
Image credit: Chanon Pornrungroj