Abstract:
Monoclinic M-phase VO2 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 (Tlum), poor solar
energy modulation ability (ΔTsol), and high phase transition temperature (Tc) can limit the
application of VO2 for smart windows. To overcome these limitations, 3D mesoporous structure
can be employed in VO2 films. Herein, 3D mesoporous structures assembled from monoclinic
M-phase VO2 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 Tlum = 67.3%,
ΔTsol = 12.5%, and lowering Tc to 63.15 °C. This is because the 3D mesoporous structure can
offer the uniform dispersion of VO2 nanoflakes in the film to enhance Tlum, ensure sufficient
VO2 nanoflakes in the film for high ΔTsol and lower Tc. Therefore, this work can provide a green
approach to synthesize 3D mesoporous structures assembled from monoclinic M-phase
VO2 nanoflakes and promote their application in smart windows.
