An international team of researchers led by Drexel University has found that a thin coating of MXene, a type of two-dimensional nanomaterial that has been discovered and studied at Drexel University for more than a decade, enhances the material’s ability to trap and release heat. have been found to be able to enhance This discovery, related to his MXene’s ability to modulate the passage of ambient infrared radiation, could lead to advances in thermal clothing, heating elements, and new materials for radiant heating and cooling.
The group, which includes materials science and optoelectronics researchers at Drexel and computational scientists at the University of Pennsylvania, wrote in a paper by Elsevier titled “Variation in the infrared properties of MXenes,” on the radiative heating and cooling functions associated with MXenes. We recently published our findings. Today’s journal material.
“This study reveals yet another aspect of the versatility of MXene materials,” said Dr. Yury Gogotsi, lead professor of the study and Bach Principal Professor at the prestigious University of Technology Drexel. increase. “MXene coatings have an excellent ability to trap and emit infrared radiation, while remaining extremely thin (200-300 times thinner than a human hair), lightweight and flexible, providing excellent localized coverage. Applications can be found in both simple thermal management and large-scale radiant heating and cooling systems.Passive infrared heating and cooling have larger applications than traditional active infrared heating and cooling, which require power to function. There are advantages.”
MXenes are a family of two-dimensional nanomaterials, first discovered by Drexel researchers in 2011, whose composition and two-dimensional structure allow them to conduct electricity, store electrical energy, filter compounds, and emit electromagnetic radiation. It has been increasingly proven to be superior in blocking , among other features. Over the years, the materials scientist has produced and extensively investigated his MXenes with different chemical compositions. As a result, a large number of applications were discovered.
In their recent paper, the team measured the ability of 10 MXene compositions to help or block the passage of infrared light, a measure called ’emissivity’. This correlates with the ability to passively capture or dissipate ambient heat.
“We knew from previous work that MXenes are capable of more than reflecting or absorbing radio and microwave radiation, so the next step was to look at their interaction with infrared radiation, which has much shorter wavelengths. said co-investigator Danzhen Zhang. – Postdoctoral Fellow in Gogotsi’s lab and co-author of the paper. “The advantage of being able to control the passage of infrared radiation is that this type of radiation can be used for passive heating if it can be contained, or for passive cooling if it can be dissipated. We have shown that we can do both, depending on the elemental composition and the number of atomic layers.”
According to Tetiana Hryhorchuk, currently available passive cooling materials on the market are capable of channeling thermal infrared radiation (body temperature) from the body through lightweight, porous fiber compositions, whereas MXene-coated fibers It works even better. A postdoctoral fellow in Gogotsi’s lab and co-author of the study, these coated textiles have the ability to reflect external infrared radiation, avoiding heating by the sun, while also allowing the body to emit infrared radiation. Because it has the additional ability to pass radiation.
Researchers found that niobium carbide MXenes can effectively dissipate heat, but titanium carbide, after being heated on a hot plate at 110 degrees for 5 minutes, only heats up to 43 degrees Celsius, showing outstanding heat. Showed shielding.
“High emissivities like niobium carbide are possible with dielectric materials,” says Gogotsi. “But MXenes combine this ability with electrical conductivity, which means that these MXenes of him can also be used as active electric heating elements with an external power supply.”
A coating of titanium carbide MXene has been found to enhance the material against infrared transmission and radiation. In tests, MXene-coated materials performed better at shielding infrared radiation than polished metal, which is currently the best-performing commercial material, even when the coating is thin. This means her MXenes can be incorporated into lightweight clothing that keeps the wearer warm in extreme environments.
To test it, the team dyed a cotton T-shirt with a titanium carbide MXene solution and used an infrared thermal camera to monitor the wearer’s body temperature. The results showed that the MXene-coated shirt kept the wearer about 10-15 degrees Celsius (about room temperature) cooler than someone wearing a regular T-shirt.
These results demonstrate that MXene-coated garments are effective at retaining body heat while also having the advantage of being applied via a relatively simpler dip-coating process than most thermal garments require. It is suggested to also provide
“Commercial winter clothing uses very thin polymer fibers with low thermal conductivity, such as fleece,” says Lingyi Bi, a postdoctoral fellow in Gogotsi’s lab and a textile expert. says. “It keeps us warm by minimizing heat transfer through the fabric. To do this effectively, it has to be very thick. It keeps us warm by preventing heat from escaping.Therefore, the MXene coating, which is thinner than silk, can provide effective warming.This is similar to the Mylar worn by runners after races in cold weather. It’s the same principle used in thermal blankets.”
Gogotsi suggests that the IR blocking feature could also be used to camouflage people and equipment from heat-sensing devices, or covertly transmit information via radio frequency identification codes visible only to infrared readers. increase.
The team will continue to study the mechanisms underlying MXene’s IR-blocking and luminescent behavior, and will test MXenes with different chemical compositions to optimize their potential as radiative heating and cooling materials.
Original: Thermal paints — MXene spray coatings can utilize infrared radiation for heating or cooling.
Than: Drexel University
