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

Abstract

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.