In-situ stirring assisted hydrothermal synthesis of W-doped VO2 (M) nanorods with improved doping efficiency and mid-infrared switching property

Vanadium dioxide (VO2) is considered to be one of the most competitive thermochromic materials, due to its semiconductor-metal phase transition characteristics. And the doping of tungsten (W) into the lattice of VO2 can significantly reduce the phase transition temperature to near room temperature. However, the reduction efficiency dependent on doping amount is quite different in previous reports. In this work, we proposed an in-situ stirring assisted hydrothermal to synthesize W-doped VO2 nanorods with improved doping efficiency. The effects of in-situ stirring during the hydrothermal synthesis on phase composition, sample morphology, and phase-transition temperature of VO2 with different W doping amounts were studied systematically. The phase transition temperature reduction efficiency of W-doped VO2 prepared by hydrothermal synthesis without in-situ stirring was at % W. By contrast, the phase transition temperature of W-doped VO2 prepared by in-situ stirring hydrothermal synthesis was depressed as much as 24.55 °C/at % W when W/V ranged in 0.75–2.0 at %. Further research found that the phase transition temperature of W-doped VO2 (M) could be simply tuned by changing the in-situ stirring time. Then, the 1 at% W-doped VO2 (M) (with phase transition temperature of around 41.5 °C) nanorods and acrylic resin were mixed to prepare VO2 composite film. It exhibited suitable infrared transmission (>60%) and excellent mid-infrared transmission switching performance (23.77%). This work proposed an in-situ stirring hydrothermal method for high efficiency synthesis of W-doped VO2 (M) and provided significant insights for its application in thermochromic windows.