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Solar Powered Coating Developed for Self-Cleaning Surfaces

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The surface coated with titanium dioxide (bottom) looks very different from the non-coated sample (top).
credit: Fraunhofer IGB

Today’s technology is not just about smart gadgets, but also about smart materials that possess self-cleaning capabilities as well. Talking about progress, even cleaning is becoming more time and energy-efficient.

Scientists belonging to the Fraunhofer Photocatalysis Alliance, which is composed of ten Fraunhofer Institutes, are conducting research on titanium dioxide.

Titanium dioxide is a photocatalyst; UV light from the sun’s ray activates it. Once activated, it triggers an electrochemical reaction that produces free radicals, which are very reactive species.

Free radicals can destroy bacteria, fungi and similar organisms. They attack by disrupting the cellular walls of these organisms; once they enter the cytoplasm, they cause irreparable damage to the cell organelles and the DNA.

Scientists are exploiting the action of titanium dioxide to design self-cleaning materials resistant to algae, moss, bacteria and fungi.

An example is the research group of Dr. Iris Trick from the Fraunhofer Institute for Interfacial Engineering and Biotechnology IGB. Her group developed a photocatalytic coating containing titanium dioxide as the active component.

They conducted an experiment using two plastic armrests; one was coated with the photocatalytic coating and the other was not coated. A mixture of various bacteria, mosses, algae and fungi was sprayed on the two armrests, and these were left exposed to the weather for two years. After the allotted time, the uncoated armrest was crusted with dirt that was virtually impossible to clean. In contrast, the coated armrest was still relatively clean and white.

The coatings were also tested on various surfaces to determine how well they work and what organic elements they destroy.

The research group from the Fraunhofer Institute for Manufacturing Engineering and Automation IPA is taking another approach. They are working on paints for building facades with titanium dioxide particles. These will be self-cleaning walls where photocatalysis degrades organic contaminants.

The research group from Fraunhofer Institute for Surface Engineering and Thin Films IST is working on coatings containing titanium dioxide for glass surfaces. Dr. Michael Vergohl, head of the department, says a possible application will be in smartphone screen to remove skin oils and fingerprints. All that is needed for self-cleaning is one hour of sunlight, unlike previous photocatalytic surfaces that require three days.

Future research direction for the Fraunhofer Photocatalysis Alliance would be finding new materials that can be activated by artificial light.

[ via eurekalert]

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