New visible light photocatalyst kills bacteria, even after light turned off

Jan 19, 2010

In the battle against bacteria, researchers at the University of Illinois have developed a powerful new weapon - an enhanced photocatalytic disinfection process that uses visible light to destroy harmful bacteria and viruses, even in the dark.

Based upon a new catalyst, the disinfection process can be used to purify drinking water, sanitize surgical instruments and remove unwanted fingerprints from delicate electrical and optical components.

"The new catalyst also has a unique catalytic memory effect that continues to kill deadly pathogens for up to 24 hours after the light is turned off," said Jian Ku Shang, a professor of materials science and engineering at the U. of I.

Shang is corresponding author of a paper that is scheduled to appear in the , and posted on the journal's Web site.

Shang's research group had previously developed a catalytic material that worked with visible light, instead of the required by other catalysts. This advance, which was made by doping a titanium-oxide matrix with nitrogen, meant the disinfection process could be activated with sunlight or with standard indoor lighting.

"When visible light strikes this catalyst, electron-hole pairs are produced in the matrix," Shang said. "Many of these electrons and holes quickly recombine, however, severely limiting the effectiveness of the catalyst."

To improve the efficiency of the catalyst, Shang and collaborators at the U. of I. and at the Chinese Academy of Sciences added nanoparticles to the matrix. The palladium nanoparticles trap the electrons, allowing the holes to react with water to produce oxidizing agents, primarily hydroxyl radicals, which kill bacteria and viruses.

When the light is turned off, the palladium slowly release the trapped , which can then react with water to produce additional oxidizing agents.

"In a sense, the material remembers that it was radiated with light," Shang said. "This 'memory effect' can last up to 24 hours."

Although the disinfection efficiency in the dark is not as high as it is in visible light, it enables the continuous operation of a unique, robust catalytic disinfection system driven by solar or other illumination.

In addition to environmental applications, the new catalyst could also be used to remove messy, oily fingerprints from optical surfaces, computer displays and cellphone screens, Shang said.

Explore further: Researchers bring clean energy a step closer

Related Stories

Sunlight turns carbon dioxide to methane

Mar 05, 2009

Dual catalysts may be the key to efficiently turning carbon dioxide and water vapor into methane and other hydrocarbons using titania nanotubes and solar power, according to Penn State researchers.

The sweet smell of nano-success

Jan 27, 2006

Materials scientists at Lehigh University and catalyst chemists at Cardiff University have uncovered secrets of the "nanoworld" that promise to lead to cleaner methods of producing, among other things, spices and perfumes.

Recommended for you

Researchers bring clean energy a step closer

Feb 27, 2015

For nearly half a century, scientists have been trying to replace precious metal catalysts in fuel cells. Now, for the first time, researchers at Case Western Reserve University have shown that an inexpensive metal-free catalyst ...

The construction of ordered nanostructures from benzene

Feb 27, 2015

A way to link benzene rings together in a highly ordered three-dimensional helical structure using a straightforward polymerization procedure has been discovered by researchers from RIKEN Center for Sustainable ...

Superatomic nickel core and unusual molecular reactivity

Feb 27, 2015

A superatom is a combination of two or more atoms that form a stable structural fragment and possess unique physical and chemical properties. Systems, that contain superatoms, open a number of amazing possibilities ...

NETL invents improved oxygen carriers

Feb 24, 2015

One of the keys to the successful deployment of chemical looping technologies is the development of affordable, high performance oxygen carriers. One potential solution is the naturally-occurring iron oxide, ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.