Double in-situ synthesis of highly dispersed VO2-Mg1.5VO4 porous film with excellent optical performance and durability for advanced smart windows

[Display omitted] •Using coordinate compound as the precursor to adjust film structure controllably.•Different decomposition temperature of VOC2O4 and Mg-VOC2O4 results in the isolated VO2 nanoparticles and porous structure.•VO2@Mg1.5VO4 porous film delivers outstanding optical properties and robust durability. Vanadium dioxide (VO2) has attracted widespread attention for application in smart windows owing to its abrupt change in near-infrared transmittance during the metal-insulator phase transition. In this study, VO2-Mg1.5VO4 films with porous structure and well-dispersed VO2 nanoparticles were prepared via a double in-situ synthesis method. The thermal decomposition products of VO2 and Mg1.5VO4 were obtained at different temperatures. Mg1.5VO4 played a role in isolating VO2 nanoparticles based on its post-formation. The obtained composite films exhibit an excellent optical performance based on antireflection of porous structure and the localized surface plasmon resonance of isolated VO2 nanoparticle, with luminous transmittance (Tlum) up to 70.0% and solar modulation ability (ΔTsol) of 12.2%. Simulation further confirms that porous structure and isolated VO2 nanoparticle can collectively enhance Tlum and ΔTsol. Moreover, ΔTsol could retain 87% after 744 h of aging at 100°C and 50 % humidity (equal to 20 years under ambient conditions). This strategy opens a facial but powerful avenue to manipulate the comprehensive performance of VO2 thermochromic film via structural engineering for the deployment of smart windows.