Direct synthesis of thermochromic VO2 through hydrothermal reaction

•One-step synthesis of thermochromic VO2 monoclinic phase, and VO2 (A and B phases) using hydrothermal technique. VO2 (A), VO2 (B).•Identification of the relationship between synthesis conditions and the morphology/structure of the final products.•Formation of VO2 monoclinic phase with an interesting hollow sphere shape.•Demonstration of superior thermal stability of the VO2 monoclinic phase.•Characterizing the thermochromic properties of VO2 monoclinic phase.

Thermochromic VO2 was directly synthesized using hydrothermal techniques. The effects of formation conditions on the structure and morphology of the final product were studied through X-ray diffraction (XRD), and scanning electron microscopy (SEM). Unique hollow sphere morphology was observed for the synthesized VO2 powders. Ex-situ XRD studies after heat treatment confirmed the thermal stability of the VO2 structure. Thermochromic properties, as a consequence of the reversible structural transformation between monoclinic VO2 and tetragonal phases, were observed by Fourier transform infrared spectroscopy (FTIR).

Graphical abstractThermochromic VO2 crystals with hollow spherical and asterisk shape were directly synthesized using hydrothermal techniques. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) studies confirmed the thermal stability and the reversible thermochromic properties of the VO2 structure.Figure optionsDownload full-size imageDownload as PowerPoint slide