Regulation of metal doping and grain size for Cr2O3 to accomplish hyperspectral camouflage properties with high near-infrared reflectance, large red-edge slope, and low visible reflectance

The advancement of hyperspectral detection technology has challenged the development of hyperspectral camouflage materials. Despite the high spectral similarity of existing bio-inspired hyperspectral materials, their poor weather resistance limits their application in harsh environments. To address this, it is essential to enhance the weather resistance of hyperspectral materials while maintaining high spectral similarity. Therefore, inorganic hyperspectral materials are employed to improve durability. However, these inorganic materials generally exhibit lower spectral similarity and insufficient near-infrared reflectance, which restricts their ability to match the spectral characteristics of diverse plant backgrounds. To enhance spectral and color similarity with green plants, this study investigates Cr 2-x Ti x O 3 , which exhibits low visible reflectance and high near-infrared reflectance. The impact of annealing temperature on reflectance (400–1300 nm) was assessed using SEM, XRD, XPS, and UV–Vis–NIR spectroscopy. The influence of free carrier concentration and particle size on reflectance was analyzed. Hyperspectral coatings based on Cr 2-x Ti x O 3 were prepared, demonstrating tunable hyperspectral reflectance. Results indicate that Cr 2-x Ti x O 3 annealed at 1100 °C has the highest near-infrared reflectance, largest red-edge slope, and tunable range, with low visible reflectance. Ultimately, the optimized spectral similarity of these coatings can reach 97 %, coupled with superior environmental durability.