Electrochemical Exfoliation of Antioxidant Ti3C2Tx MXene Flakes With Humidity-Responsive Emissivity for Adaptive Infrared Camouflage.

Ti3C2Tx MXene exhibits metal-comparable low emissivity, ultralow density, and good flexibility for infrared camouflage. However, it suffers from critical challenges such as susceptibility to hydrolytic oxidation and difficulty in dynamically matching the thermal radiation characteristics of the background environment. Therefore, this work innovatively proposes an electrochemical exfoliation strategy to prepare the highly antioxidative and emissivity-tunable Ti3C2Tx MXene flakes, which differs from the conventional liquid-phase ultrasonic exfoliation method. Chitosan electrolytes intercalate into adjacent interlayer galleries, which significantly reduces the exfoliation difficulty and achieves a high monolayer exfoliation yield of 85%. More importantly, the surface modification can effectively resist the erosion of water and oxygen molecules, maintaining structural integrity and emissivity stability of Ti3C2Tx MXene flakes over 50 days. Furthermore, the electrochemically exfoliated Ti3C2Tx MXene shows a humidity-responsive emissivity through adsorption and desorption of water molecules within interlayer galleries. Notably, the emissivity tuneability is exogenous-energy-free, continuously reversible, and highly repeatable with a wide tuning range of 0.32. The electrochemically exfoliated Ti3C2Tx MXene not only achieves superior static infrared camouflage for targets, but also dynamically matches the thermal radiation characteristics of the background with ambient humidity, thus realizing an adaptive infrared camouflage. This work will promote the development of MXene-based adaptive infrared camouflage.