Preparation of VO2/Al-O core-shell structure with enhanced weathering resistance for smart window

VO 2 /Al-O core-shell structure (V/AO) was synthesized by a facile method and its application for thermochromic film on smart window was investigated. Comparisons of thermochromic properties and stabilities in different environments between VO 2 and annealed V/AO nanoparticles were made. As a result, VO 2 nanoparticle was easily oxidized and lost thermochromic property. In contrast, with the protection provided by Al-O-based shell, the VO 2 core remained stable at a high temperature (350   °C in air) and in H 2 O 2 solution. Especially, thermochromic films made by annealed V/AO nanoparticles almost kept thermochromic performance in damp heating environment (T=60   °C, RH=90%) for 20 days while VO 2 films lost their thermochromic properties after 3 days. Besides, the degradation progress of VO 2 and V/AO nanoparticles in damp heating environment was also explored. Results indicate that Al-O-based shell provides a good protection for the VO 2 core originated from the compact structure of shell, which effectively prevents oxygen and water from eroding VO 2 . In summary, the VO 2 nanoparticles coated with Al-O-based shell exhibit a great potential in the application of smart window.