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A new 2-D material uses light to quickly and safely purify water

In tests, it killed 99.9999 percent of the bacteria in contaminated water

Using light, a prototype “green” material can purify enough daily drinking water for four people in just one hour. In tests, it killed nearly 100 percent of bacteria in 10 liters of water, researchers report February 7 in Chem.

This new material, a 2-D sheet of graphitic carbon nitride, is a photocatalyst: It releases electrons when illuminated to create destructive oxygen-based chemicals that destroy microbes. The design avoids pitfalls of other similar technology. Today’s most effective photocatalysts contain metals that can leach into water as toxic pollutants. Others are non-metallic, like the new 2-D sheets, but are less efficient because they hold onto electrons more tightly.

Materials scientist Guoxiu Wang of the University of Technology Sydney and colleagues created ultrathin sheets of graphitic carbon nitride and added chemical groups like acids and ketones that lure electrons toward the sheets’ edges. There, the electrons jump onto oxygen atoms in water to form such microbe-dissolving oxygen chemicals as hydrogen peroxide.

The design killed 99.9999 percent of bacteria, including E. coli, in a 50-milliliter water sample. That’s as efficient as the best metal-based catalyst. And it killed microbes more quickly than previous best metal-free photocatalysts, which take over an hour to achieve what the new design did in 30 minutes.

The team then attached the nanosheets to the inside surface of plastic bags, purifying 10 liters of water in an hour.

“Our motive was to develop an efficient way to use sunlight to produce water for undeveloped or remote regions without a central supply of clean water,” Wang says, noting that the carbon and nitrogen composition should make the material inexpensive. The researchers next aim to work with engineers to scale up the design for commercial use.


By Jeremy Rehm

I'm a current graduate student in Santa Cruz, California at the University of California, Santa Cruz Science Communication Program, training to become a science journalist.

I grew up in little Carlisle, Pennsylvania, where I spent my days exploring the outdoors, teaching my Beanie Babies the ropes of Greek mythology and linguistics, writing reports on planets and the Cosmos, and absorbing every ounce of science I could understand.

For years, I struggled to decide what major I would study at Brigham Young University, but in the end, I found a compromise: a Bachelor of Science in biology and two minors in chemistry and music. I would have done math and astronomy as well. I then went on to Brown University to complete my Master of Science in ecology and evolutionary biology.

It was there that I first learned of science journalism, and that there was such a field to take my passion for communication and science and turn it into my career.   

See more of his work at or follow him on Twitter @jrehm_sci.

(Source:; February 12, 2019;
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