Ultralow and Selective Infrared Emission from MXenes.

Low and selective infrared emission materials are necessary for next generation thermal technologies, including passive heating, infrared identification, and photothermal conversion. Here, we report on the intrinsic infrared radiation properties of three MXenes: Ti3C2Tx, Ti3CNTx, and V4C3Tx. The infrared emissivity of 200 nm thick Ti3C2Tx coating is lower than 0.06 between wavelengths of 3-27 {\mu}m, while Ti3CNTx and V4C3Tx have values of 0.13 and 0.26, respectively. Investigation using a laboratory-based passive heating process showed that MXene coatings suppress the thermal radiation. The infrared identification capability was also validated using a patterned MXene fabric. This work paves the way for developing MXene-based smart wearable devices and garments capable of selective and localized thermal management.