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

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 MoSe2 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 MoSe2 (CS@MoSe2) 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@MoSe2 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. 2D MoSe2 is discovered with intrinsic low infrared emissivity and is further exfoliated into adequately aminated nanosheets with nice thermal camouflage performance. Experimental and density functional theory calculations together reveal mechanisms to affect infrared emissivity as electron–photon reflection and phonon–photon absorption. This work offers inspiration for two‐dimensional materials selection and preparation toward desired infrared radiation properties in certain wavebands to satisfy numerous applications.