Combined Experimental and DFT Study on 2D MoSe2 toward Low Infrared Emissivity

Abstract Low infrared emissivity materials play a key role in thermal camouflage or retardation. Among these, fillers can be easily shaped into various flexible forms and normally provide an omnidirectional and polarization‐insensitive emissivity. However, conventional fillers suffer from drawbacks of full‐waveband ultrahigh reflectivity, unsatisfactory thermal camouflage performances, or poor chemical/thermal stabilities. Herein, 2D MoSe 2 is discovered as a new semiconductor with intrinsic low infrared emissivity after first‐principle density functional theory calculation and experimental demonstration on eight types of two‐dimensional materials (2DMs). Mechanisms of electron–photon reflection and phonon–photon absorption for the low infrared emissivity are proposed. A two‐step microwave‐assisted amination process is developed to exfoliate the nanosheets and obtain a desired low infrared emissivity. The as‐obtained chitosan modified MoSe 2 (CS@MoSe 2 ) has an ultrahigh spectral reflectivity of 78%–86% in 8–14 µm, and its resin‐based coating still exhibits a low infrared emissivity of 0.32 and shows a dramatic reduction in radiation temperature of 28 °C for a hot object at 70 °C. Besides, CS@MoSe 2 can endure a high temperature of 220 °C and is demonstrated with a long‐term thermal camouflage efficiency in hot environments. This work will guide 2DMs selection and preparation toward desired infrared radiation properties to satisfy numerous applications.