Synthesis and characterization of MXOY(M=Ti, Si, Zn, Al) coated VO2 nanorods

The world's available energy resources have been diminishing since the beginning of the 21th century. Saving enerygy is one of the best way to solve this problem. Vanadium Dioxide (VO2) is a widely studied inorganic phase change material, which has a reversible phase transition from semiconducting monoclinic to metallic rutile phase at a critical tempreture of Tc=68 C. The abrupt decrease of infrared transmittance in the metallic phase makes VO2 a potential candidate for thermochromic smart windows to cut down building energy consumption. But in applications, due to some limitations, researchers face with some issues like high Tc, low luminious transmittance, undesirable solar modulation ability and instability for enviromental effects. In order to tackle these issues, many approaches such as elementary doping and coating have been proposed. Among them, coated nanostructure is one the most effective methods for offering solutions to many of these issues. In the first stage of this study, VO2 nanostructures were synthesized by one of the most common methods, hydrothermal method then their phase was changed to to monoclinic phase under appropriate annealing conditions. Then, proposed core@shell structures (VO2@SiO2, VO2@TiO2, VO2@Al2O3, VO2@ZnO) were prepared by coating VO2 nanorods with various metal oxides. The coated structures were dissolved in DMF and added to the solution of PVB to prepare thermochromic films. Results indicated that the coated structure of VO2 made improvements in the phase transition temperature and optical properties and stability of VO2 nanorods. These structures are thought to be promising for thermochromic applications.