SLAC, Stanford scientists advance water-purification technology


Take a bottle of water contaminated by certain types of bacteria, drop into the water a new and inexpensive nanotechnology device about half the size of a postage stamp and resembling a piece of black glass, and set the bottle in the sunlight. In 20 minutes, the bacteria will be dead and the water will be clean, according to an announcement from the SLAC National Accelerator Laboratory in Menlo Park and Stanford University.

Tests show the device killing three specific strains of bacteria in water prepared in a lab, not the "complex stews of contaminants found in the real world," but there's reason to think that it would be fatal to other types of bacteria and microbes, including viruses, SLAC said.

The device could supersede traditional techniques of water decontamination, including boiling, which requires fuel, or placing containers of contaminated water in sunlight to allow the ultraviolet light to kill the bacteria, which takes six to 48 hours, scientists say.

The device employs walls of molybdenum disulfide a few atoms thick, topped by a thin layer of copper and arranged like a labyrinth on a small black rectangle of glass.

Sunlight falling on ultra-thin layers of molybdenum disulfide causes its electrons to migrate, scientists say. The result: electrically charged particles that leave behind electrically charged holes. With copper present as a catalyst, the situation favors chemical reactions, they say, including a reaction that creates hydrogen peroxide, a common disinfectant.

"Molybdenum disulfide is cheap and easy to make – an important consideration when making devices for widespread use in developing countries," said Yi Cui, an associate professor and investigator at Stanford and SLAC. "It also absorbs a much broader range of solar wavelengths than traditional photocatalysts."

"It's very exciting to see that by just designing a material you can achieve a good performance. It really works," said Chong Liu, a postdoctoral researcher and lead author of the report. She is also working on a project to develop air filters to defeat smog. "Our intention is to solve environmental pollution problems so people can live better."

Funding for the project comes from the U. S. Department of Energy through the Stanford Institute for Materials and Energy Sciences at SLAC, and done in collaboration with Stanford's Department of Civil and Environmental Engineering.


Follow the Almanac on Twitter and Facebook for breaking news, local events and community news.

We can't do it without you.
Support local journalism.


Like this comment
Posted by Noob
a resident of College Terrace
on Aug 21, 2016 at 9:33 pm

While large-scale billion dollar water purifying plants are yet to be built in every 3rd world country, this is a great step to solving the global water crisis. FUND THIS! Good job stanford

Like this comment
Posted by Cedric de La Beaujardiere
a resident of Barron Park
on Aug 22, 2016 at 9:40 am

Cedric de La Beaujardiere is a registered user.

This is an exciting development. I wonder though how they assure that the hydrogen peroxide comes in contact with all the bacteria. Does it need some mixing process, or does it behave like a gas in a room, which expands to evenly distribute itself through the space (as I was taught)?

Sorry, but further commenting on this topic has been closed.

Don't be the last to know

Get the latest headlines sent straight to your inbox every day.

Rose International Market reopens in Mountain View
By Elena Kadvany | 11 comments | 5,957 views

The HSR Decision
By Steve Levy | 8 comments | 1,352 views

We need a new garage downtown Palo Alto -- forget about being politically correct
By Diana Diamond | 9 comments | 1,266 views

The Other Greenhouse Gas
By Sherry Listgarten | 6 comments | 1,218 views

Know Before You Buy: Understanding Senior Living Facility Agreements
By Max Greenberg | 0 comments | 682 views


Short story writers wanted!

The 33rd Annual Palo Alto Weekly Short Story Contest is now accepting entries for Adult, Young Adult (15-17) and Teen (12-14) categories. Send us your short story (2,500 words or less) and entry form by March 29. First, Second and Third Place prizes awarded in each category.

Contest Details