Enhanced Thermochromic Performance of VO2 Nanoparticles by Quenching Process

Vanadium dioxide (VO2) has been a promising energy-saving material due to its reversible metal-insulator transition (MIT) performance. However, the application of VO2 films has been seriously restricted due to the intrinsic low solar-energy modulation ability (& UDelta;T-sol) and low luminous transmittance (T-lum) of VO2. In order to solve the problems, the surface structure of VO2 particles was regulated by the quenching process and the VO2 dispersed films were fabricated by spin coating. Characterizations showed that the VO2 particles quenched in deionized water or ethanolreserved VO2(M) phase structure and they were accompanied by surface lattice distortion compared to the pristine VO2. Such distortion structure contributed to less aggregation and highly individual dispersion of the quenched particles in nanocomposite films. The corresponding film of VO2 quenched in water exhibited much higher & UDelta;T-sol with an increment of 42.5% from 8.8% of the original VO2 film, because of the significant localized surface plasmon resonance (LSPR) effect. The film fabricated from the VO2 quenched in ethanol presented enhanced thermochromic properties with 15.2% of & UDelta;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 VO2 nanoparticles. In summary, the study provided a facile way to fabricate well-dispersed VO2 nanocomposite films and to facilitate the industrialization development of VO2 thermochromic films in the smart window field.