Researchers from Drexel University and the Korea Institute of Science and Technology have demonstrated that a coating of the nanomaterial MXene can effectively shield electronic devices from electromagnetic interference.

“Internal electromagnetic noise coming from different electronic parts can have a serious effect on everyday devices such as cell phones, tablets and laptops, leading to malfunctions and overall degradation of the device,” notes Babak Anasori a research assistant professor in the A.J. Drexel Nanomaterials Institute.

Researchers in Drexel's Department of Materials Science and Engineering tested samples of MXene films ranging in thickness from just a couple micrometers up to 45 micrometers, which is slightly thinner than a human hair. Their findings suggest that a several-atoms-thick titanium carbide film—one of about 20 two-dimensional materials in the MXene family discovered by Drexel University scientists—can be effective at blocking and containing electromagnetic interference, with the added benefit that it can be applied easily as a coating by spraying it onto any surface.

MXene, a nanomaterial that is both thin and light, has the ability to block and absorb electromagnetic radiation. Image credit: Drexel University.MXene, a nanomaterial that is both thin and light, has the ability to block and absorb electromagnetic radiation. Image credit: Drexel University. Their discovery is significant because a material’s shielding effectiveness—a measure of its ability to block electromagnetic radiation from passing through it—tends to increase with its thickness. For purposes of this research, the team was trying to identify the thinnest shielding material that could still effectively block the radiation.

According to the researchers, the thinnest film of MXene is competitive with copper and aluminum foils in terms of shielding effectiveness. By increasing the thickness of the MXene to 8 micrometers, they were able to achieve 99.9999% blockage of radiation with frequencies covering the range from cell phones to radars.

The thin sample of MXene performed significantly better than other synthetic shielding materials, such as graphene or carbon fibers, the researchers report. To achieve commercial electromagnetic shielding requirements, currently used carbon-polymer composites would have to be more than one millimeter thick, which would add quite a bit of heft to a device like an iPhone, which is just seven millimeters thick.

The researchers say the key to MXene’s performance lies in its high electrical conductivity and two-dimensional structure. When electromagnetic waves come into contact with MXene, some are immediately reflected from its surface. Others that pass through the surface lose energy amidst the material’s atomically thin layers. The lower-energy electromagnetic waves are eventually reflected back and forth off the internal layers until they are completely absorbed in the structure.

One other result, which portends MXene’s usefulness in protecting wearable devices, is that its shielding effectiveness is just as robust when it is combined with a polymer to make a composite coating.

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