One-step hydrothermal synthesis of tungsten-doped VO2(M) nanoparticles for application in thermochromic smart windows

Vanadium dioxide (VO 2 ) exhibits optical regulation properties in the solar band through a thermally induced insulator-to-metal phase transition near 68 ℃. Tungsten doping can decrease the VO 2 phase transition temperature ( Tc ) to near room temperature and enhance its applicability in smart windows for building energy saving. The optical regulation performance of tungsten-doped VO 2 (W-VO 2 ) is crucial for its smart window applications and varies with doping concentration. In this work, W-VO 2 nanoparticles were synthesized via a facile one-step hydrothermal method, and the effects of W doping on the Tc and particle morphology were systematically analyzed. This approach achieved a low Tc and improved optical performance without complex post-processing. The optical performance in the solar band was investigated with different doping concentrations ranging from 0.0 at to 2.0 at%. The sizes of the W-VO 2 nanoparticles ranged from 34.9 to 45.2 nm in diameter. The Tc decreased with increasing doping concentration and reached as low as 29.9 ℃ upon heating at a doping concentration of 2.0 at%. The W-VO 2 /PVP composite films exhibited excellent thermochromic performance. The luminous transmittance reached 52.71% and the solar modulation efficiency was up to 11.75% at a doping concentration of 1.0 at% and a volume fraction of 1.29%. These results demonstrate the potential of VO 2 nanoparticles in energy-saving smart window applications as a high-performance, low-cost material.