Atomic Layer Deposition Synthesis of VO2@Al–O Core–Shell Structure with Enhanced Oxidation Resistance for Adaptive Infrared Camouflage Application

VO2 has attracted extensive attention as an adaptive camouflage material due to its structural change during the metal–insulator transition (MIT) at 68 °C, which can rapidly respond to ambient temperature and actively modulate the infrared emissivity. However, its thermal instability has limited its application in the optical field. In this paper, VO2@Al2O3 core–shell micronanoparticles (VO2@Al–O) with controllable shell thickness were first prepared by the atomic layer deposition method, and their thermal stability and infrared modulation performance were systematically studied. The results indicate that VO2 is highly susceptible to oxidation (at 403 °C in air), resulting in a loss of thermochromic properties. In contrast, under the protection of the aluminum-based shell layer, the VO2 core remains stable at higher temperatures (up to 575 °C in air) and in H2O2 solutions. In addition, compared to uncoated VO2, VO2@Al–O core–shell particles also demonstrate significant infrared emissivity modulation capabilities (Δε > 0.35) in the medium-wave and long-wave thermal atmospheric windows. In summary, vanadium oxide particles coated with an aluminum-based shell layer demonstrate excellent antioxidant properties and potential for thermal camouflage applications.