Novel VO2(M)-ZnO heterostructured dandelions with combined thermochromic and photocatalytic properties for application in smart coatings

Hierarchical VO2(M)-ZnO dandelions with ZnO nanorods grown radially on VO2(M) nanoparticle cores have been successfully fabricated for the first time. In these dandelions, the VO2(M) NPs were prepared by a TiO2 seed-assisted hydrothermal method and the dandelion-like ZnO nanorods were formed over two steps: heteroseed-induced nucleation and the subsequent heteroepitaxial growth processes. The coupled ZnO could increase the chemical stability of VO2(M) at relatively high temperatures. In addition, the VO2(M)-ZnO composite film with decreased phase transition temperature (T-c = 62.6 degrees C) simultaneously displayed an enhanced visible transmission (Tvis-l = 52.2%) and solar modulating ability (Delta T-sol = 9.3%) as compared with the pure VO2(M) film. Besides, the VO2(M)-ZnO dandelions also exhibited improved photocatalytic performance, likely due to the synergistic effect of the VO2(M)-ZnO heterojunction, unique dandelion-like hierarchical structure and high specific surface area. This is the first report of such a single VO2(M)-ZnO dandelions structure with energy saving and environmental protection effects that offer significant potential for creating a multifunctional smart coating.