3D mesoporous structure assembled from monoclinic M-phase VO(2) nanoflakes with enhanced thermochromic performance

Monoclinic M-phase VO(2) is 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 VO(2) for smart windows. To overcome these limitations, 3D mesoporous structure can be employed in VO(2) films. Herein, 3D mesoporous structures assembled from monoclinic M-phase VO(2) nanoflakes with a pore size of about 2–10 nm were synthesized by a hydrothermal method using Ensete ventricosum fiber (EF) as a template followed by calcination at 450 °C. The prepared film exhibited excellent thermochromic performance with balanced T(lum) = 67.3%, ΔT(sol) = 12.5%, and lowering T(c) to 63.15 °C. This is because the 3D mesoporous structure can offer the uniform dispersion of VO(2) nanoflakes in the film to enhance T(lum), ensure sufficient VO(2) nanoflakes in the film for high ΔT(sol) and lower T(c). Therefore, this work can provide a green approach to synthesize 3D mesoporous structures assembled from monoclinic M-phase VO(2) nanoflakes and promote their application in smart windows.