Home > Press > SLAC, Stanford gadget grabs more solar energy to disinfect water faster: Plopped into water, a tiny device triggers the formation of chemicals that kill microbes in minutes
This nanostructured device, about half the size of a postage stamp, uses sunlight to quickly disinfect water. It consists of thin flakes of molybdenum disulfide arranged like walls on a glass surface and topped with a thin layer of copper. Light falling on the walls triggers formation of hydrogen peroxide (H2O2) and other “reactive oxygen species” that kill bacteria. C. Liu et al., Nature Nanotechnology |
Abstract:
In many parts of the world, the only way to make germy water safe is by boiling, which consumes precious fuel, or by putting it out in the sun in a plastic bottle so ultraviolet rays will kill the microbes. But because UV rays carry only 4 percent of the sun's total energy, the UV method takes six to 48 hours, limiting the amount of water people can disinfect this way.
Now researchers at the Department of Energy's SLAC National Accelerator Laboratory and Stanford University have created a nanostructured device, about half the size of a postage stamp, that disinfects water much faster than the UV method by also making use of the visible part of the solar spectrum, which contains 50 percent of the sun's energy.
In experiments reported today in Nature Nanotechnology, sunlight falling on the little device triggered the formation of hydrogen peroxide and other disinfecting chemicals that killed more than 99.999 percent of bacteria in just 20 minutes. When their work was done the killer chemicals quickly dissipated, leaving pure water behind.
"Our device looks like a little rectangle of black glass. We just dropped it into the water and put everything under the sun, and the sun did all the work," said Chong Liu, lead author of the report. She is a postdoctoral researcher in the laboratory of Yi Cui, a SLAC/Stanford associate professor and investigator with SIMES, the Stanford Institute for Materials and Energy Sciences at SLAC.
Nanoflake Walls and Eager Electrons
Under an electron microscope the surface of the device looks like a fingerprint, with many closely spaced lines. Those lines are very thin films - the researchers call them "nanoflakes" - of molybdenum disulfide that are stacked on edge, like the walls of a labyrinth, atop a rectangle of glass.
In ordinary life, molybdenum disulfide is an industrial lubricant. But like many materials, it takes on entirely different properties when made in layers just a few atoms thick. In this case it becomes a photocatalyst: When hit by incoming light, many of its electrons leave their usual places, and both the electrons and the "holes" they leave behind are eager to take part in chemical reactions.
By making their molybdenum disulfide walls in just the right thickness, the scientists got them to absorb the full range of visible sunlight. And by topping each tiny wall with a thin layer of copper, which also acts as a catalyst, they were able to use that sunlight to trigger exactly the reactions they wanted - reactions that produce "reactive oxygen species" like hydrogen peroxide, a commonly used disinfectant, which kill bacteria in the surrounding water.
Molybdenum disulfide is cheap and easy to make - an important consideration when making devices for widespread use in developing countries, Cui said. It also absorbs a much broader range of solar wavelengths than traditional photocatalysts.
Solving Pollution Problems
The method is not a cure-all; for instance, it doesn't remove chemical pollutants from water. So far it's been tested on only three strains of bacteria, although there's no reason to think it would not kill other bacterial strains and other types of microbes, such as viruses. And it's only been tested on bacteria mixed with water in the lab, not on the complex stews of contaminants found in the real world.
Still, "It's very exciting to see that by just designing a material you can achieve a good performance. It really works," said Liu, who has gone on to work on a project in Cui's lab that is developing air filters for combating smog. "Our intention is to solve environmental pollution problems so people can live better."
###
The work was funded by the Department of Energy Office of Science through SIMES, and carried out in collaboration with Professor Alexandria Boehm's group in the Stanford department of civil and environmental engineering.
####
About SLAC National Accelerator Laboratory
SLAC is a multi-program laboratory exploring frontier questions in photon science, astrophysics, particle physics and accelerator research. Located in Menlo Park, California, SLAC is operated by Stanford University for the U.S. Department of Energy Office of Science. To learn more, please visit www.slac.stanford.edu.
SLAC National Accelerator Laboratory is supported by the Office of Science of the U.S. Department of Energy. The Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit science.energy.gov.
For more information, please click here
Contacts:
Andrew Gordon
650-926-2282
Copyright © SLAC National Accelerator Laboratory
If you have a comment, please Contact us.Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.
Related Links |
Related News Press |
News and information
Beyond wires: Bubble technology powers next-generation electronics:New laser-based bubble printing technique creates ultra-flexible liquid metal circuits November 8th, 2024
Nanoparticle bursts over the Amazon rainforest: Rainfall induces bursts of natural nanoparticles that can form clouds and further precipitation over the Amazon rainforest November 8th, 2024
Nanotechnology: Flexible biosensors with modular design November 8th, 2024
Exosomes: A potential biomarker and therapeutic target in diabetic cardiomyopathy November 8th, 2024
Govt.-Legislation/Regulation/Funding/Policy
New discovery aims to improve the design of microelectronic devices September 13th, 2024
Physicists unlock the secret of elusive quantum negative entanglement entropy using simple classical hardware August 16th, 2024
Single atoms show their true color July 5th, 2024
Possible Futures
Nanotechnology: Flexible biosensors with modular design November 8th, 2024
Exosomes: A potential biomarker and therapeutic target in diabetic cardiomyopathy November 8th, 2024
Turning up the signal November 8th, 2024
Nanofibrous metal oxide semiconductor for sensory face November 8th, 2024
Discoveries
Breaking carbon–hydrogen bonds to make complex molecules November 8th, 2024
Exosomes: A potential biomarker and therapeutic target in diabetic cardiomyopathy November 8th, 2024
Turning up the signal November 8th, 2024
Nanofibrous metal oxide semiconductor for sensory face November 8th, 2024
Announcements
Nanotechnology: Flexible biosensors with modular design November 8th, 2024
Exosomes: A potential biomarker and therapeutic target in diabetic cardiomyopathy November 8th, 2024
Turning up the signal November 8th, 2024
Nanofibrous metal oxide semiconductor for sensory face November 8th, 2024
Interviews/Book Reviews/Essays/Reports/Podcasts/Journals/White papers/Posters
Beyond wires: Bubble technology powers next-generation electronics:New laser-based bubble printing technique creates ultra-flexible liquid metal circuits November 8th, 2024
Nanoparticle bursts over the Amazon rainforest: Rainfall induces bursts of natural nanoparticles that can form clouds and further precipitation over the Amazon rainforest November 8th, 2024
Nanotechnology: Flexible biosensors with modular design November 8th, 2024
Exosomes: A potential biomarker and therapeutic target in diabetic cardiomyopathy November 8th, 2024
Environment
Nanoparticle bursts over the Amazon rainforest: Rainfall induces bursts of natural nanoparticles that can form clouds and further precipitation over the Amazon rainforest November 8th, 2024
New method in the fight against forever chemicals September 13th, 2024
Water
Taking salt out of the water equation October 7th, 2022
The latest news from around the world, FREE | ||
Premium Products | ||
Only the news you want to read!
Learn More |
||
Full-service, expert consulting
Learn More |
||