Fig. 1 Infrared radiation properties of MXene (a) Schematic of infrared reflection and emission with MXene[18]; (b) Absorptance/emissivity spectra of Ti3C2Tx film at visible and infrared ranges[23]; (c) Room-temperature infrared emissivity spectra of different MXene coatings at wavelength range of 1-25 μm[18]; (d) Relationship between average infrared emissivity (8-14 μm) and electrical conductivity of MXene coatings[18]

Fig. 2 Infrared identification/camouflage with MXenes (a) Infrared thermal image of MXene, graphene, stainless steel, graphene oxide, and montmorillonite films on an object at 508 ℃[27]; (b) Infrared thermal images of security flower[28]; (c) Visible and (d) infrared images of different MXene coatings on a hot plate at 70 ℃, showing the identification capability of MXenes due to their varying colors and infrared emissivity[18]; (e) Infrared camera images of the patterned device before and after local near infrared (NIR) irradiation to demonstrate information encryption and display applications[29]

Fig. 3 Surface plasmon of MXene (a) Electronenergy loss spectroscopy (EELS) analysis of a Ti3C2Tx flake[33]; (b) EELS fitted intensity maps of the corresponding surface plasmon modes and inherent interband transition sustained by the flake at the energy losses[33]; (c) Schematic of Ti3C2Tx based nanodisks array[34]; (d) Improvement of absorption spectra of patterned Ti3C2Tx film[34]

Fig. 4 Photothermal conversion with MXene (a) Schematic of photothermal energy conversion and storage of the PEG/Ti3C2Tx composites[42]; (b) Temperature evolution curves of the composites under the simulated sunlight irradiation[42]; (c) Temperature change of the coated crystal with the increasing power of infrared radiation[43]; (d) Time-dependent temperature increase of the surface of the composites upon illumination with infrared light (744 mW) at 25 ℃[43]; (e) Temperature elevations at the tumor sites of 4T1-tumor-bearing mice under different treatments during laser irradiation[39]; (f) Time-dependent tumor growth curves after different treatments[39]

Fig. 5 Infrared photodetection with MXene (a) Structural diagram of Ti3C2Tx-RAN photodetector[49]; (b) Dynamic optical response curves of Au-RAN and Ti3C2T-RAN photodetector with insets showing optical photos of the device[49]; (c) Schematic of the MAPbI3/Nb2CTx photodiode[50]; (d) Responsivity and detectivity of the MAPbI3/Nb2CTx photodiode under different white light intensities[50]