3D mesoporous structure assembled from monoclinic M-phase VO₂nanoflakes with enhanced thermochromic performance

Monoclinic M-phase VO₂is a promising candidate for thermochromic materials due to its abrupt change in the near infrared (NIR) transmittance along with the metal-to-insulator transition (MIT) at a critical temperature ∼68 °C. However, low luminous transmittance (T_lum), poor solar energy modulation ability (ΔT_sol), and high phase transition temperature (T_c) can limit the application of VO₂for smart windows. To overcome these limitations, 3D mesoporous structure can be employed in VO₂films. Herein, 3D mesoporous structures assembled from monoclinic M-phase VO₂nanoflakes with a pore size of about 2-10 nm were synthesized by a hydrothermal method usingEnsete ventricosumfiber (EF) as a template followed by calcination at 450 °C. The prepared film exhibited excellent thermochromic performance with balancedT_lum= 67.3%, ΔT_sol= 12.5%, and loweringT_cto 63.15 °C. This is because the 3D mesoporous structure can offer the uniform dispersion of VO₂nanoflakes in the film to enhanceT_lum, ensure sufficient VO₂nanoflakes in the film for high ΔT_soland lowerT_c. Therefore, this work can provide a green approach to synthesize 3D mesoporous structures assembled from monoclinic M-phase VO₂nanoflakes and promote their application in smart windows.