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

Abstract

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 (Tlum), poor solar energy modulation ability (ΔTsol), and high phase transition temperature (Tc) 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 balancedTlum= 67.3%, ΔTsol= 12.5%, and loweringTcto 63.15 °C. This is because the 3D mesoporous structure can offer the uniform dispersion of VO2nanoflakes in the film to enhanceTlum, ensure sufficient VO2nanoflakes in the film for high ΔTsoland lowerTc. 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.