A research team from the University of Cambridge has developed an innovative floating device that uses solar energy to convert contaminated or seawater into clean hydrogen fuel and purified water.

The device can operate on any open water source and does not rely on external power sources, making it particularly beneficial for regions with limited resources or without access to the electrical grid.

Innovation inspired by nature

Inspired by photosynthesis, the process by which plants convert sunlight into food. But unlike previous versions of “artificial leaves” that could produce green hydrogen fuel from clean water sources, this new device can work from polluted or seawater sources and produce clean drinking water at the same time.

Tests of the device have shown that it can produce clean water from highly polluted water, seawater and even the River Cam in central Cambridge.of result reported in a magazine natural water.

Technical challenges and breakthroughs

“It’s difficult to combine solar fuel production and water purification into a single device,” said study co-lead author Dr Chanon Pornunglozi from the Yusuf Hameed Department of Chemistry at the University of Cambridge. “Solar-powered water splitting, where water molecules are split into hydrogen and oxygen, requires starting with completely pure water, as contaminants can poison the catalyst or cause unwanted chemical side reactions. .”

“Water splitting is extremely difficult in remote and developing regions, where clean water is relatively scarce and the infrastructure needed to purify water is not readily available,” said co-lead author Arifin. Mohammad Annua said. “If we have a device that works with contaminated water, we could potentially solve two problems at once: we could split water to make clean fuel and we could make clean drinking water.”

Researchers have developed a solar-powered floating device that can turn contaminated or seawater into clean hydrogen fuel or purified water anywhere in the world. Credit: Chanon Pornrungroj/Ariffin Mohamad Annuar

Pornunglozi and Mohammad Annua, members of Professor Irwin Reisner’s research group, have devised a design that does just that. They deposited a photocatalyst on a nanostructured carbon mesh that easily absorbs both light and heat, producing water vapor that the photocatalyst uses to produce hydrogen. The porous carbon mesh treated to repel water facilitated the levitation of the photocatalyst and served to keep it away from the water below so that pollutants would not interfere with the photocatalyst’s function.

Additionally, new devices use more solar energy. “The process of using light to produce solar fuels uses only a small portion of the solar spectrum; much of the spectrum remains unused,” said Mohammad Anuar.

The research team used a white UV-absorbing layer on top of the floating device for hydrogen production through water splitting. The rest of the solar spectrum travels to the bottom of the device, where the water evaporates.

“This way, we are making better use of light. We get steam for hydrogen production, and the rest is water vapor,” Pornunglozi said. “This way we can now incorporate the process of transpiration, so we can really mimic real leaves.”

Potential global impact

A device that can create clean fuel and clean water all at once using only solar power could help address the energy and water crisis facing many parts of the world. For example, according to the World Health Organization, indoor air pollution caused by cooking with “dirty” fuels such as kerosene is responsible for more than 3 million deaths a year. Cooking with green hydrogen instead could potentially reduce that number significantly. And around the world, he said, 1.8 billion people still don’t have safe drinking water at home.

“The design is also very simple. In just a few steps, you can build a device that works well with water from a variety of sources,” said Mohammad Anuar.

“It is very resistant to contaminants, and the floating design allows the substrate to work in very murky or muddy water,” Pornungloj said. “It’s a very versatile system.”

“While our device is still a proof of principle, these solutions will be needed to develop a truly circular economy and sustainable future,” said Reisner, who led the research. Stated. “The climate crisis and issues around pollution and health are closely linked, and developing approaches that help address both could be a game-changer for many people.”

References: “Hybrid photothermal-photocatalytic sheets for solar-powered whole water splitting coupled with water purification” by Chanon Pornrungroj, Ariffin Bin Mohamad Annuar, Qian Wang, Motiar Rahaman, Subhajit Bhattacharjee, Virgil Andrei, Erwin Reisner; November 13, 2023 natural water.
DOI: 10.1038/s44221-023-00139-9

This research was partially supported by the European Commission’s Horizon 2020 programme, the European Research Council, the Cambridge Trust, the Petronas Educational Sponsorship Program and the Winton Program for the Physics of Sustainability. Erwin Reisner is a fellow at St. John’s College. Chanon Pornrungroj is a member of the University of Darwin and Ariffin Mohamad Annuar is a member of Clare University.