Enhanced Thermochromic Performance of VO 2 Nanoparticles by Quenching Process.

Vanadium dioxide (VO 2 ) has been a promising energy-saving material due to its reversible metal-insulator transition (MIT) performance. However, the application of VO 2 films has been seriously restricted due to the intrinsic low solar-energy modulation ability (Δ T sol ) and low luminous transmittance ( T lum ) of VO 2 . In order to solve the problems, the surface structure of VO 2 particles was regulated by the quenching process and the VO 2 dispersed films were fabricated by spin coating. Characterizations showed that the VO 2 particles quenched in deionized water or ethanolreserved VO 2 (M) phase structure and they were accompanied by surface lattice distortion compared to the pristine VO 2 . Such distortion structure contributed to less aggregation and highly individual dispersion of the quenched particles in nanocomposite films. The corresponding film of VO 2 quenched in water exhibited much higher Δ T sol with an increment of 42.5% from 8.8% of the original VO 2 film, because of the significant localized surface plasmon resonance (LSPR) effect. The film fabricated from the VO 2 quenched in ethanol presented enhanced thermochromic properties with 15.2% of Δ T sol and 62.5% of T lum . It was found that the excellent T lum resulted from the highly uniform dispersion state of the quenched VO 2 nanoparticles. In summary, the study provided a facile way to fabricate well-dispersed VO 2 nanocomposite films and to facilitate the industrialization development of VO 2 thermochromic films in the smart window field.