Synthesis of VO2 nanoparticles for thermochromic applications

Smart materials have collected increasing attention in recent years, particularly in energy-efficient applications, because of their capacity to react actively to external stimuli. The thermochromic properties of vanadium dioxide (VO2), which are mainly associated with the metal-insulating phase transition the compound experiences when heated to about 68°C, make it stand out among these kinds of materials and indicate great promise. Because of this crucial feature, VO2 is appropriate for applications such as optical switches, sensors, and smart windows. It is difficult to obtain the target VO2 phase (VO2(M1)) among the numerous polymorphic phases of this oxide, which are difficult to control experimentally. This study examined and optimized the synthesis of VO2 nanoparticles using hydrothermal techniques and thermal treatments. Vanadyl acetylacetonate (VO(acac)2) and vanadyl sulfate (VOSO4) were used as precursors to produce VO2 in the required phase. Temperature, reaction time, reagent concentration, and the method of adding the reductant were the most important synthesis parameters examined. These factors were assessed in order to determine how they affected the material's morphology, optical characteristics, and crystalline phase. UV-Vis-NIR spectroscopy and X-ray diffraction (XRD) were the main methods used to characterize the resulting nanoparticles. The findings demonstrated how the formation of the various polymorphic phases of VO2 is significantly influenced by the choice of precursor and synthesis conditions. In particular, the use of VOSO4 under suitable conditions allowed the production of stable VO2(M1) nanoparticles with good thermochromic characteristics.